Remove use stricts from ts files

This is implicit for modules

basic-multi-root-sample/src/extension.ts

@@ -2,8 +2,6 @@
  * Copyright (C) Microsoft Corporation. All rights reserved.
  *--------------------------------------------------------*/
 
-'use strict';
-
 import { ExtensionContext, StatusBarAlignment, window, StatusBarItem, Selection, workspace, TextEditor, commands } from 'vscode';
 import { basename } from 'path';