CI: add ruff linting job, fix PEP8/257 violations and formatting

[deltragon]

CC #589

There should be no functional changes in the code, only formatting.

Note: I originally used flake8+black here, however I switched to ruff as it is a single tool that can check more than the other two (eg. docstrings).

Note: Once this is merged, we should probably add a step for installing/running ruff to the wiki page: https://github.com/slgobinath/SafeEyes/wiki/Run-from-Source

[deltragon]

Well, also looks like the Github Action is working.

[deltragon]

Note to self: Apparently black also has a GitHub Action, so maybe use that instead/in addition.

[nifadyev]

Hey @deltragon , I suppose we should wait for @archisman-panigrahi opinion first. Then we'd better discuss and agree on linter and linter rules
It is awesome that you have already made some changes but personally preferred linting rules is not much better than no rules at all

[deltragon]

@nifadyev I agree, I would definitely wait for sign-off from all maintainers here.
In my experience, it is helpful for the discussion to have a specific proposal started, and implementing this didn't take too long - most of this is automatic.

Regarding the chosen style - it seems that the Python community in general has standardized around PEP8 and PEP257, and the official black formatter, which this PR implements. (It uses ruff instead of black/flake8/etc, as it is a single tool that can check all the rules, instead of needing multiple tools - but the rules/formatting stay the same.)

[archisman-panigrahi]

I am traveling, and didn't follow any conversation since last weekend. I will get back this sunday

[nifadyev]

it is helpful for the discussion to have a specific proposal started

Good point, @deltragon , especially if it does took much time

I will leave comments with suggested linting rules if you don't mind

[deltragon]

@nifadyev Feel free to, I'd appreciate them! I don't have strong opinions to be honest, I just want it to be consistent (and auto-enforced).

[nifadyev]

In my opinion, such docstrings are not helpful and could be removed or partially placed into method name. This could be a point in our code styleguide

[deltragon]

I agree. Are there linter rules that we could use that would help with that?
As with the other ones, I would leave this for a future PR as well.

[nifadyev]

Looks great @deltragon , much better than now. Still a lot to do though.

[deltragon]

@nifadyev In general, these are good suggestions.
However, they are mostly purely additive to the changes in this PR, and can be added in a later PR that implements extra rules. I would prefer that they not hinder this PR from being merged.

[nifadyev]

LGTM @deltragon

Thank you for this important task, I hope the codebase will be much cleaner and single styled now. Agreed about changes, they shall be made in separate PR. Maybe create an issue or some Markdown document with changes to make (or discuss)?

[deltragon]

@nifadyev I've opened #642 to track the future improvements.