Issue Type: Feature Request

Webviews in web are iframes hosted on azure websites which is not in the same origin as the vscode web, so it can't access modules from vscode in the same way as running in Desktop. In notebook, we are using vs/loader.js as the builtin AMD loader in the webview, to make it work in Web, IMHO we need to bundle vs/loader.js together with other webview resources (main.js, pre.js, etc).

VS Code version: Code - Insiders 1.45.0-insider (a3083e5, 2020-04-17T08:08:39.508Z)
OS version: Darwin x64 19.2.0