The vscode extension should be cleaned up and released

I think it would be nice if the vscode extension was released and polished and usable for Buck2. I have it installed locally, but it's a chore especially when using features like remote vscode.

What would be needed for this? Ideally it would be released through GitHub as well, which would be really nice to help people contribute.

A tricky thing is how much buck2-specific "stuff" should be in it. The extension is distributed with the starlark package, but right now buck2 is the main user. Ideally, buck2 *specific* integration would include things like running or listing build targets...