* Adding ICompletionExtension interface
* Adding extension loading and execution logic
* Fixing compilation error in VS 2017
* Using MEF for completion extension discovery
* using await on GetCompletionItems
* Adding an integration test for completion extension and update the completion extension interface
* Update the completion extension test
* Fix issues based on review comments
* Remove try/cache based on review comments, fix a integration test.
* More changes based on review comments
* Fixing SendResult logic for completion extension loading
* Only load completion extension from the assembly passed in, add more comments in the test
* Adding right assert messages in the test.
* More fixes based on review comments
* Dropping ICompletionExtensionProvider, load assembly only if it's loaded at the first time or updated since last load.
* Fix based on the latest review comments
* Adding missing TSQL functions in default completion list
* Update jsonrpc documentation for completion/extLoad
* Fix https://github.com/Microsoft/vscode-mssql/issues/986 and add better server edition naming
- Fixed a number of issues related to the binding queue, specifically the fact that it didn't capture exceptions that occurred on the binding thread. This caused the thread to crash the service.
- The root cause of the error was when you get a connection error during init of the SmoMetadataProvider which threw an exception. Because of this no Binder was created, and the code would null ref later during processing
- Added logic to handle null ref issue and other related code
- Added a unit test for the new error handling path, and supported still returning some value in this case
- Separately, have a fix for an issue where the edition is shown as "SQL Azure" for all Azure connections. Fixing to be "Azure SQL DB" for this case and handle when the database reports as DW or Stretch instead. This maps better to users concept of what the edition should be and avoids returning what is an outdated term.
* Messed up the test - fixing this by returning the expected return object
