[Enhancement] Support vscode.dev web environment

[mattmasson]

Changes will be required to make the Power Query language service extension compatible with the vscode.dev web environment.

https://code.visualstudio.com/api/extension-guides/web-extensions#web-extension-enablement

vscode.dev now supports LSP based extensions, but it looks like it will require some code changes to make it work.
https://code.visualstudio.com/api/extension-guides/web-extensions#language-server-protocol-in-web-extensions