Azure: add PostgresSQL support and refactor to use resource graph (#8046)

* Azure: add PostgresSQL support and refactor to use resource graph
- Refactored to use @azure/arm-resourcegraph for all queries
- Refactored database lookup to do just 2 queries
(all servers, all DBS) instead of waiting serially on 1 query per RG
- Added Azure Database for PostgresSQL Servers support in the tree
- Removed use of older azure APIs in preference to ones compatible with resource graph
- Note: Had to use v1.0 of new subscriptions package because resourcegraph is 2month out of date vs all other packages

extensions/azurecore/src/azureResource/tree/accountTreeNode.ts

@@ -5,11 +5,12 @@
 
 import { TreeItem, TreeItemCollapsibleState } from 'vscode';
 import { Account, NodeInfo, AzureResource } from 'azdata';
-import { TokenCredentials } from 'ms-rest';
-import { AppContext } from '../../appContext';
+import { TokenCredentials } from '@azure/ms-rest-js';
+
 import * as nls from 'vscode-nls';
 const localize = nls.loadMessageBundle();
 
+import { AppContext } from '../../appContext';
 import { azureResource } from '../azure-resource';
 import { TreeNode } from '../treeNode';
 import { AzureResourceCredentialError } from '../errors';

extensions/azurecore/src/azureResource/tree/subscriptionTreeNode.ts

@@ -3,8 +3,6 @@
  *  Licensed under the Source EULA. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-'use strict';
-
 import { TreeItem, TreeItemCollapsibleState } from 'vscode';
 import { Account, NodeInfo } from 'azdata';
 import { AppContext } from '../../appContext';