Bundle extension during packaging step

[cbandera]

Recently we get this warning during the Packaging step in CI

Warning: This extension consists of 3043 files, out of which 2244 are JavaScript files. For performance reasons, you should bundle your extension: https://aka.ms/vscode-bundle-extension. You should also exclude unnecessary files by adding them to your .vscodeignore: https://aka.ms/vscode-vscodeignore.

This should be addressed.

[cameron-martin]

There's an open but stale PR for this: #421