PR: Handle empty options in pycodestyle and pydocstyle preferences

[dalthviz]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)
• Included a screenshot or animation (if affecting the UI, see Licecap)

Issue(s) Resolved

Fixes #9209

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[dalthviz]

@ccordoba12 testing the behavior of the two options (select and ignore), what I see is that when you use the select option, only the warnings selected are shown (the other ones are ignore). Also, the select option takes precedence to the ignore option, so for example if you put for the select and ignore options the E202 code, only the warnings associted with an E202 warning will be shown

[ccordoba12]

Thanks @dalthviz for testing how things work. If that's the case, then I think we should leave both select and ignore options active and let users decide what they want to do with them.

But perhaps an explanation should be added to our docs. @CAM-Gerlach, what do think?

[ccordoba12]

Pretty nice usage of list comprehensions! 👍

[ccordoba12]

Merging because pycodestyle accepts both select and ignore, as @dalthviz pointed out.

The question about mentioning this in our docs is a separate issue.

[CAM-Gerlach]

Thanks, @ccordoba12 . I created spyder-ide/spyder-docs#96 to cover this.