Add check to make sure only strings are assigned to __name__

[ninezerozeronine]

Steps

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• Add a ChangeLog entry describing what your PR does.
• If it's a new feature or an important bug fix, add a What's New entry in doc/whatsnew/<current release.rst>.
• Write a good description on what the PR does.

Description

This adds a new check to make sure that only strings are assigned to __name__ attributes.

Type of Changes

	Type
✓	✨ New feature

Related Issue

Closes #583

[ninezerozeronine]

Putting this in as a draft to check I'm going in the right direction.

I'd like to:

• Add inference to detect things like:

def return_string():
    return "foo"

def my_func():
    pass

my_func.__name__ = return_string()

• Investigate how using inference relates to confidence levels and add this to the check output if necessary.
• Improve check output to include more details of why the check failed.

[PCManticore]

Hey @ninezerozeronine

Thank you for sending this PR! Overall it's looking great, left a bunch of comments to be addressed before we can pull this in.

[ninezerozeronine]

Thank you for the advice and examples Claudiu! I'm hoping to take a stab at this this weekend.

[coveralls]

Coverage increased (+0.02%) to 89.864% when pulling d0851ab on ninezerozeronine:feature/check-dundername-is-string into 1e84b02 on PyCQA:master.

[coveralls]

Coverage increased (+0.02%) to 89.864% when pulling d0851ab on ninezerozeronine:feature/check-dundername-is-string into 1e84b02 on PyCQA:master.

[coveralls]

Coverage increased (+0.02%) to 89.865% when pulling d0851ab on ninezerozeronine:feature/check-dundername-is-string into 1e84b02 on PyCQA:master.

[PCManticore]

Thanks a lot for the patch @ninezerozeronine !