Initial commit for Query Store extension (#23260)

* Initial commit for Query Store extension

* fix eslint explicit-functino-return-type setting

* address comments

* remove specifying explicit-function-return-type eslint rule

* update strings

extensions/query-store/extension.webpack.config.js

@@ -0,0 +1,17 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+//@ts-check
+
+'use strict';
+
+const withDefaults = require('../shared.webpack.config');
+
+module.exports = withDefaults({
+	context: __dirname,
+	entry: {
+		extension: './src/extension.ts'
+	}
+});