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/objectExplorerNodeProvider/fileSources.ts

@@ -16,6 +16,7 @@ import * as nls from 'vscode-nls';
 
 import * as constants from '../constants';
 import { WebHDFS, HdfsError } from './webhdfs';
+import * as auth from '../util/auth';
 
 const localize = nls.loadMessageBundle();
 
@@ -84,11 +85,13 @@ export interface IHdfsOptions {
 
 export interface IRequestParams {
 	auth?: IHttpAuthentication;
+	isKerberos?: boolean;
 	/**
 	 * Timeout in milliseconds to wait for response
 	 */
 	timeout?: number;
 	agent?: https.Agent;
+	headers?: {};
 }
 
 export interface IHdfsFileStatus {
@@ -106,10 +109,10 @@ export class FileSourceFactory {
 		return FileSourceFactory._instance;
 	}
 
-	public createHdfsFileSource(options: IHdfsOptions): IFileSource {
+	public async createHdfsFileSource(options: IHdfsOptions): Promise<IFileSource> {
 		options = options && options.host ? FileSourceFactory.removePortFromHost(options) : options;
 		let requestParams: IRequestParams = options.requestParams ? options.requestParams : {};
-		if (requestParams.auth) {
+		if (requestParams.auth || requestParams.isKerberos) {
 			// TODO Remove handling of unsigned cert once we have real certs in our Knox service
 			let agentOptions = {
 				host: options.host,
@@ -119,6 +122,11 @@ export class FileSourceFactory {
 			};
 			let agent = new https.Agent(agentOptions);
 			requestParams['agent'] = agent;
+
+		}
+		if (requestParams.isKerberos) {
+			let kerberosToken = await auth.authenticateKerberos(options.host);
+			requestParams.headers = { Authorization: `Negotiate ${kerberosToken}` };
 		}
 		return new HdfsFileSource(WebHDFS.createClient(options, requestParams));
 	}