* Add checker `using-final-in-unsupported-version`
This is one of the tasks in issue: #5134
Also:
- Ensure the existing checkers for `typing.final` are used irrespective of Python
version
* Emit `using-final-in-unsupported-version` warning when Python version < 3.8
and none of the other `typing.final`-related warnings
* Add `uninferable_final_decorators`
Return any `typing.final` decorators for a given `Decorators` node.
Used to determine if this decorator is used with a version of Python in
which it is unsupported.
Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>
