Fix some ICEs and annoyances surrounding `!` type

- Don't attempt to autoderef `!`.  The `Deref`/`DerefMut` trait lookup would generate a bunch of unhelpful error spew.
- Don't allow explicit deref of `!`, since later passes just ICE.  This closes issue #17373 
- Don't allow explicit index of `!`, since later passes just ICE.  There does not seem to be an issue associated with this