Make invalid type ignore comments non-blocking (#13506)
Blocking errors are a bad user experience and there's no reason for this
one to be one / there is another code path for invalid type ignores that
is non-blocking.
Fixes half of #12299. The half it doesn't fix is that ideally users
shouldn't be getting these warnings from third party libraries.
Also see https://github.com/python/mypy/issues/12162#issuecomment-1212554729
But that's for another PR
