Migrate github extension to ESM (2nd attempt) (#248312)

* Revert "GitHub - revert ESM migration (#247322)"

This reverts commit 2047ab0fff.

* use `"@vscode/extension-telemetry": "^1.0.0"` which doesn't use default export anymore

extensions/github/extension.webpack.config.js

@@ -1,17 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. 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'
-	}
-});