Why not use wslview as proposed in #173?

I wanted to, and actually based this change on it (it uses powershell under the hood). However it doesn't support passing additional arguments to the underlying start command in powershell and therefore wouldn't allow implementing the wait/app options.

With this change, I guess the url option is moot? Since it was added because of & escaping problems on Windows. Maybe we should just remove that option now?

It's up to you really, that would be a breaking API change, but it—theoretically—won't actually break any existing usages if it's removed.

Let me know if you'd prefer to remove it as part of this change or not.

We can remove it from the JS code, but it has to stay in the index.d.ts file (with a doc comment that it will be removed in the next major release).