PR fixes the issue when the user is unable to sign in with Google.
In the end, my assumption about the `User-Agent` header was correct and Google sign-in works with the recent Electron out of the box.
The old JS-based Welcome Screen was removed and replaced with the Rusty one.
Co-authored-by: Adam Obuchowicz <adam.obuchowicz@enso.org>
Co-authored-by: Adam Obuchowicz <adam.obuchowicz@luna-lang.org>
