* Add LanguageFlavorNotification handling and refactor LanguageService
- Added new notification handler for language flavor changed
- Refactored the LanguageService so that it no longer relies on so many intertwined static calls, which meant it was impossible to test without modifying the static instance. This will help with test reliability in the future, and prep for replacing the instance with a service provider.
* Skip if not an MSSQL doc and add test
* Handle definition requests
* Fix diagnostics handling
* Ensure connection open for OE queries and fix connection disposal
- Dispose connection in Metadata service, to ensure we cleanly dispose and don't rely on garbage colleciton
- Fixed issue where if the connection was closed, expanding databases in the Server would fail. This is because SMO doesn't always reopen the connection, certainly not for Server level queries. The solution is to always check if open and reopen.
- Added unit tests for this, which required mocking the relevant IsOpen / OpenConnection methods. Refactored SMO wrapper calls into a dedicated class file to handle this
* Fix the OE service where retuns database as the root node if the connection contains database name
* Fix OE tests
* addressed the comments
* addresses comment
* fix OE test and add more tests
* fix VerifyAdventureWorksDatabaseObjects test
