Web extension

[ratmice]

There are a few impediments to making this work as a web-extension, vscode-web is probably worth looking at too

first need to compile to wasm, tower-lsp-wasm is a good example, but shows we need to use something other than tokio.
after that we would encounter threads, and the route filesystem stuff through workspace.fs.

I believe workspace.fs is probably vscode-specific, so we'd need to keep around the existing direct-to-filesystem code
and either make the web-extension a feature or entire branch at first...

I think it is worth pursuing, perhaps after the diagnostics are a bit more friendly

Edit:
Also need to look at vscode-wasm which if I understand, could eventually allow us to replace the entirety of the javascript with rust compiled to wasm, this seems like it should be possible as we aren't spawning any processes doing things not supported by wasi itself other than filesystem stuff discussed above.