Add more typing

- Attempt to type all functions
- Change namedtuples to tryuped NamedTuples
- Add checks for optional / None variables
- Lots of isinstance replacing getattr etc.
- Add b005 to visit_ImportFrom
- Found bug in check_for_b020 for reassigned_in_loop checking
  - Need to handle comprehensions

A lot of AI here, so happy to revert anything that
does not make sense.

Test:
- `pre-commit run -a`
- `tox -e mypy`

Author: cooperlees