Extension deprecation: Bundle extensions with the VS Code extension

Created by: philipp-spiess

Closes #39353 (closed)

With this diff, the VS Code extension:

• No longer uses the user settings to get a list of extensions to load
• No longer queries the extension registry
• No longer downloads extension code from a remote URL

To do this, we had to make two changes:

1. Change client/vscode/src/webview/platform/context.ts and supply a getStaticExtensions() callback. When this returns something, we no longer load extension based on the config object.
2. Add a script to download and build the code intelligence extensions and make sure they are bundled with the release artifact. This script is inspired by the one that we use in BExt to make a bundle for Firefox but it uses a 2 year newer code intel snapshot. Since building all of the extensions is rather slow, I've added some caching as well.

Test plan

• Manual testing using DevTools to find out which network requests are made (and aren't anymore).

The code intel features works the same as before:

Before

After

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.