Add snippet tests using mypy

[Josverl]

The Goal is to run mypy across all check_ and feature_ folders by re-use the same approach as for the pyright snippet test.

Parsing mypy output
There is no simple way to get machine readable output from mypy

• Support more output formats python/mypy#10816

workaround: regex hack in the mypy-vscode extension:

• https://github.com/matangover/mypy-vscode/blob/25487c286328099fe2f2d26393c59c63bea45881/src/extension.ts#L503-L530C2
• https://github.com/matangover/mypy-vscode/blob/25487c286328099fe2f2d26393c59c63bea45881/src/mypy.ts#L1-L2

import re

pattern = r'^(?P<file>[^:\n]+):((?P<line>\d+):)?((?P<column>\d+):)? (?P<type>\w+): (?P<message>.*)$'

Changes to stubs:
One challenge is that mypy does not allow a replacement stdlib to be used , at least not for all modules.
Specificaly the sys.pyi module seems to be a blocker as mypy just refuses to run if it is included.
A simple /blunt approach would be to just delete the typings/sys.pyi file before running the test.

[Josverl]

implemented in : Josverl/micropython-stubs#739