* adding context
* apply extension changes
* shimming disconnect
* add data explorer context menu and add disconnect to it
* clean up shim code; better handle errors
* remove tpromise
* simplify code
* add node context on data explorer
* formatting
* add new Query action
* fix various errors with how the context menus work
* add manage and new query
* add refresh command
* formatting
* Fix#4029 Ensure changeKernels always resolves, even in error states
This is necessary to unblock reverting the kernel on canceling Python install
- startSession now correctly sets up kernel information, since a kernel is loaded there.
- Remove call to change kernel on session initialize. This isn't needed due to refactor
- Handle kernel change failure by attempting to fall back to old kernel
- ExtensionHost $startNewSession now ensures errors are sent across the wire.
- Update AttachTo and Kernel dropdowns so they handle kernel being available. This is needed since other changes mean the session is likely ready before these get going
* Fix to handle python cancel and load existing scenarios
- Made changes to handle failure flow when Python dialog is canceled
- Made changes to handle initial load fail. Kernel and Attach To dropdowns show No Kernel / None and you can choose a kernel
- Added error wrapping in ext host so that string errors make it across and aren't lost.
* Fix#4452 Notebook is reloaded with wrong kernel
- Await all extension registration before getting providers and providerId
To do this, we need to await way up in the NotebookInput, and promise the model that we'll have values eventually
* change shutdown to use proper notification
* change to use storage service
* remove unused imports
* fix test
* change shutdown methods to private
* remove unusde imports
* fix tests
* formatting
* #4339: Kernel change event occurs after model load
* #4347: Code cleanup - Notebooks Save
* Remove save method from sqlops
* Adding save method to api's
* Adding save method to ext host
* Misc change
* Fix#4356 New Notebook from connection doesn't connect
Fix new notebook error by passing profile instead of ID.
- I could've just sent the ID over, but this fix sets the stage for disconnected connections to work (since we have enough info to properly connect).
- There's a bug in NotebookModel blocking the disconnected connection part working, but Yurong's in progress fixes will unblock this. Hence checking in as-is and working to properly unblock once that's in.
* Support connection profile in commandline service
- Added new context API for things that want to work on commandline and object explorer
- Refactored commandlineservice slightly to be async & have a simpler execution flow (far fewer if/else statements)
* Fix unit tests
- Fixed 2 issues raised by tests (sholdn't do new query if no profile passed, shouldn't error on new query failing)
- Updated unit tests to pass as expected given changes to the APIs.
* Start single client session based on the default kernel or saved kernel in NB.
* Added kernel displayName to standardKernel.
Modified name to allign wtih Juptyer Kernel.name.
So we can show the displayName during startup and use the name to start the session.
* Change session.OnSessionReady event in KernelDropDown
* Added model.KernelChnaged for switching kernel in the same provider
* Fixed session.Ready sequence
* Fixed merge issues
* Solve merged issue
* Fixed wrong kernel name in saved NB
* Added new event in Model to notify kernel change.
Toolbar depends on ModelReady to load
* Change attachTo to wait for ModelReady like KenelDropDown
* sanitizeSavedKernelInfo to fix invalid kernel and display_name. For example: PySpark1111 and PySpark 1111
* Added _contextsChangingEmitter to change loadContext msg when changing kernel
* Resolve PR comments
* check to see whether options is available
* removing options state and using _modelOptions
* removed additional space
* making options getter private as not intended to expose
* adding context
* apply extension changes
* shimming disconnect
* add data explorer context menu and add disconnect to it
* clean up shim code; better handle errors
* remove tpromise
* simplify code
* add node context on data explorer
* formatting
* fix various errors with how the context menus work
* adding context
* apply extension changes
* shimming disconnect
* add data explorer context menu and add disconnect to it
* clean up shim code; better handle errors
* remove tpromise
* simplify code
* Add azdata.d.ts for new extensibility APIs
* Update azdata typing files for connection API proposal
* Add implementation for azdata module
* Fix build break in agent
- Fixes#4129 Overlapping command help windows in notebook
- Do not show parameter hints for inactive cells, to avoid them hanging around when no longer selected
- Fixes#4116 Notebooks: Intellisense Doesn't Work using Add New Connection
- Move connect/disconnect logic to 1 place (code component) instead of 2
- Handle the case where you connect after choosing active cell. We now hook to the event and update connection
- Fix issues in sql session manager where result outputs 0 rows. This was failing to show the empty resultset contents, which is a regression vs. query editor. It also put unhandled error on the debug console
- Fix#3913 Notebook: words selected in other cells should be unselected on cell change
Note: after fix, now looks as follows. Need to do follow up to get correct grid min height

* added initial data explorer viewlet
* added dataexplorer contribution point
* removed test view
* remove unused imports
* inital data source, needs work
* add shim for ext host
* formatting
* making the necessary changes to use OE for tree view; need to look at TreeUpdateUtils.connectAndCreateOeSession
* formatting
* shimming oe more
* update to add correct context
* working cross provider; need to fix connection
* connection works but it adds the connection to the oe for some reason
* formatting
* add custom connection dialog code path
* hashing between trees
* added flag and tests
* add id maps to handle multiple nodepaths
* add necessary car edit parts
* keep current behavior in prodc
* fix tests
* address comments
* update comments to be more informative
* finish merge
* update comments
* fix whitespace
* Move to using notebook language by default, with override in cell
* Update cell language on kernel change
* Tweak language logic so that it prefers code mirror mode, then falls back since this was failing some notebooks
* Add new package.json contribution to define language magics. These result in cell language changing. Language is cleared out on removing the language magic
* Added support for executing Python, R and Java in the SQL Kernel to prove this out. It converts to the sp_execute_external_script format
TODO in future PR:
* Need to hook up completion item support for magics (issue #4078)
* Should add indicator at the bottom of a cell when an alternate language has been detected (issue #4079)
* On executing Python, R or Java, should add some output showing the generated code (issue #4080)
* working on formatting
* fixed basic lint errors; starting moving things to their appropriate location
* formatting
* update tslint to match the version of vscode we have
* remove unused code
* work in progress fixing layering
* formatting
* moved connection management service to platform
* formatting
* add missing file
* moving more servies
* formatting
* moving more services
* formatting
* wip
* moving more services
* formatting
* move css file
* add missing svgs
* moved the rest of services
* formatting
* changing around some references
* formatting
* revert tslint
* revert some changes that brake things
* formatting
* fix tests
* fix testzx
* fix tests
* fix tests
* fix compile issue
* Greatly reduce time to generate html table string
* change outer tag to table instead of html
* address PR feedback for more descriptive variable name
- Fix#3844
- Fix#3955
- Specs can be null on early load of Jupyter kernels
- Cells were missing in some reference test .ipynb files. We should be resilient to malformed files if possible.
* Fixed#3954
The problem is: connectionProfileId is not passed into New Notebook flow.
The fix is: plumbing connectionProfileId via NotebookInput.
* Resolved PR comments
* Fix#3985 Hide cell toolbar for markdown cells
* Note that I'm still hiding the overall toolbar section per UX feedback
* Also now hiding line numbers per UX feedback..
Fixes#3931
- Align run button correctly so it's centered in new cell
- Refactor to support multi-state button.
- Hidden state is set to show execution count
- Stopped state shows run button
- Running state shows stop button
- Error state (will) show error button. This isn't fully handled right now
- Add execution count to model and to SqlKernel, verify serialization, loading, update matches other notebook viewers
**Notes on implementation**:
I think this is a decent solution for a) showing execution count as text, and b) perfectly centering the run button.
The below solution shows count correctly up to 999 runs (that’s clicking 999 times in a single session), the icon lines up juuust about right with [ ] but for other numbers it is pretty close but probably not exactly right. I wish I could solve this to work better but trying to change text float to center etc. really isn’t working.
**Screenshots**:

With running cell:

* upgrade plan is piped through and returns the xml plan
* Added review deploy plan page
* checkbox validation now working and columns formatted
* formatting and cleaning up code
* refactored populateTable()
* addressing comments
* addressing comments
* updating tooltips
* add padding to table cells to align with headers
* fix problems when going back and forth between pages and changing config options
* bump sqltoolsservice version to 71
* fix localization
- Handles empty file scenario, with fixes along the way for missing metadata (bonus win)
- In non-empty file still shows error and kernel stuck in loading state. #3964 opened to track this issue and fix later