More typing (#15449)

## Description:

More typing improvements.

Switch to using `mypy.ini` for flexibility

Add `warn_return_any` check except in `homeassistant.util.yaml` that does typing hacks. Fix some type annotations as resulting from this check and ignore others were fixing is hard.

## Checklist:
  - [x] The code change is tested and works locally.
  - [x] Local tests pass with `tox`. **Your PR cannot be merged unless tests pass**