Remove flake8-executable dependency

[sobolevn]

We need to vendor this dependency to our own codebase:

• create new violation
• create new logical check
• write tests

Implementation: https://github.com/xuhdev/flake8-executable/blob/abf67771703b2f06f02a3fedb1dd97299583a4c3/flake8_executable/__init__.py#L92-L128

Related: #1139

[sobolevn]

But, we only need a single violation for this. Let's call it ExecutableMismatchViolation and change its error message instead. Not the code.

[adambenali]

I'd like to work on it !

[sobolevn]

🤝 thanks a lot!

[sobolevn]

@pandaseal does this plugin work on Windows without building?

[pandaseal]

Yes the plugin works.

• I works in Windows natively (in cmd and Powershell)
• It works in the home dir of the WSL
• It does not work in the windows partion of the WSL (but this is not due to the plugin but the overwriting of permissions problem)

However, the reason the build does not work on windows is the UnicodeDecodeError referenced in issue #337 and tests failing

[sobolevn]

@pandaseal you would do us a big (like 2 years big) favour if you tackle this windows build issue down. I don't own a windows machine and too lazy to setup and an emulation, so this is an actual problem for us that is not solved for 2 years now.

We can even bring back the windows CI with https://docs.travis-ci.com/user/reference/windows/

If you are willing to work on this, we can reopen #337