Scaffold out basic markdown language server (#154293)

* Scaffold out basic markdown lsp

This scaffolds out a new markdown language server and then uses it to implement document symbols. After the change, the markdown extension will have the following structure:

- languageService — Where all the LSP language stuff will eventually land
- server — The actual language server. Consumes ` languageService`
- src — The current extension that launches the server and implements VS Code specific functions

* Adding build scripts

* a

* Use language service from github

* Remove ls build scripts

* Bump versions

* Only build ext

* Enable for web

* Fixing for browser

extensions/markdown-language-features/server/extension-browser.webpack.config.js

@@ -0,0 +1,24 @@
+/*---------------------------------------------------------------------------------------------
+ *  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 withBrowserDefaults = require('../../shared.webpack.config').browser;
+const path = require('path');
+
+module.exports = withBrowserDefaults({
+	context: __dirname,
+	entry: {
+		extension: './src/browser/main.ts',
+	},
+	output: {
+		filename: 'main.js',
+		path: path.join(__dirname, 'dist', 'browser'),
+		libraryTarget: 'var',
+		library: 'serverExportVar'
+	}
+});