Start to separate coding standards and best practices to their own rulesets

[javorszky]

Base ruleset is WordPress-Core.

Thinking:

• is it something that is covered by PSR1 or PSR2? -> coding style
• is it something that isn't WP specific, isn't covered by PSR1 or PSR2, but relates to how the code looks and other code styles may or may not have a rule to it? -> coding style
• everything else is a best practice

Have a look at the files. I'll go through WordPress-Extra and separate the extras / overrides from that onto either of these. Not sure how to handle the layered approach to be honest.

Would a WordPress-Extra-CodingStyle and WordPress-Extra-BestPractices make sense that just imported the previous ones?

Won't that fragment the rulesets?

[jrfnl]

Hi @javorszky Thank you for your willingness to contribute and for this PR.

Unfortunately, I will close this PR at this time as this has been discussed several times before - see issues #740, #1067, #1157, #1269 - without consensus being reached.
I would kindly like to ask you to contribute to and continue the discussions in those issue(s). If and when consensus would be reached and this PR would be in line with it, we can always re-open the PR.