Initial AD support for BDCs (#6741)

Partially working AD support for BDCs with some known issues
- Plumbed through kerberos support to Notebooks.
  - Using "gateway-0" for service temporarily as service endpoints API doesn't yet return correct DNS name. Will update in separate PR once available
- Plumbed kerberos auth to HDFS, Spark. Only partially working as we use same token on each call 
  - Will fix in separate PR, as this requires a refactor of WebHDFS library. Will need to either get new token every time or set a cookie, both of which require refactors
- Fixed error when Data Service node expansion failed and blocked all OE expansion
- Support for SqlToolsService change to use new cluster endpoints DMV
  -  Updated API to add new endpoints field to replace IP + port
  - Added logic to handle case where endpoints for Yarn, Grafana etc. are in the list
  - Sort list and use expected new localized strings

- Updated SqlToolsService to include support for new DMV
- Add "gateway-0" handling in Jupyter session as workaround for lack of domain names in endpoints list

extensions/mssql/src/config.json

@@ -1,6 +1,6 @@
 {
 	"downloadUrl": "https://github.com/Microsoft/sqltoolsservice/releases/download/v{#version#}/microsoft.sqltools.servicelayer-{#fileName#}",
-	"version": "2.0.0-release.2",
+	"version": "2.0.0-release.4",
 	"downloadFileNames": {
 		"Windows_86": "win-x86-netcoreapp2.2.zip",
 		"Windows_64": "win-x64-netcoreapp2.2.zip",