Initial SQL Project tree viewlet in Explorer sidebar (#8639)

* Adding mock contents for tree
* added open sqlproj dialog
* reading files from directory
* Added directory traversal
* Adding tree sorting by folder vs file and label
* Improved auto-unfolding of tree based on node type
* replacing fs with fs.promise alias
* added activation event for when workspace contains sqlproj files
* Returning after displaying error

extensions/sql-database-projects/src/extension.ts

@@ -0,0 +1,24 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import MainController from './controllers/mainController';
+
+let controllers: MainController[] = [];
+
+export async function activate(context: vscode.ExtensionContext): Promise<void> {
+	// Start the main controller
+	const mainController = new MainController(context);
+	controllers.push(mainController);
+	context.subscriptions.push(mainController);
+
+	await mainController.activate();
+}
+
+export function deactivate(): void {
+	for (let controller of controllers) {
+		controller.deactivate();
+	}
+}