Mount HDFS Dialog: basic support (#7580)

Implemented in this PR

- New base dialog for anything needing to work with the controller. This is important since going from SQL -> Controller we "should" have the right permissions but aren't guaranteed
- Support for Mount HDFS via a dialog. Includes basic polling for success/failure, but have to give up after 2.5min as mounting could take hours. By then it's assumed to be successful since server-side has 2min timeout built in.


Not implemented in this PR

- Script as Notebook button. This should convert the inputs to a set of cells in a notebook so users can run things themselves
- Updates based on PM / UX reviews. I think we'll need a round of feedback before completing this work.

extensions/big-data-cluster/package.json

@@ -45,6 +45,10 @@
 				{
 					"command": "bigDataClusters.command.manageController",
 					"when": "false"
+				},
+				{
+					"command": "bigDataClusters.command.mount",
+					"when": "false"
 				}
 			],
 			"view/title": [
@@ -70,6 +74,13 @@
 					"when": "view == sqlBigDataCluster && viewItem == bigDataClusters.itemType.controllerNode",
 					"group": "navigation@3"
 				}
+			],
+			"objectExplorer/item/context": [
+				{
+					"command": "bigDataClusters.command.mount",
+					"when": "nodeType=~/^mssqlCluster/ && nodeType!=mssqlCluster:message && nodeSubType=~/^(?!:mount).*$/",
+					"group": "1mssqlCluster@10"
+				}
 			]
 		},
 		"commands": [
@@ -97,6 +108,10 @@
 			{
 				"command": "bigDataClusters.command.manageController",
 				"title": "%command.manageController.title%"
+			},
+			{
+				"command": "bigDataClusters.command.mount",
+				"title": "%command.mount.title%"
 			}
 		]
 	},