Support trait abstract method docstring inheritance and validation

[evolbug]

Feature request

Hi! Since PHP 8.0, declared abstract trait method signatures are statically enforced at definition time, they are no longer just suggestions, similar to inheriting from an abstract class, so it would make sense if docstrings would also be passed down.

This would avoid the need of copy-pasting docsctrings and having to keep them in sync. There is a previous issue opened by @Firehed in reference to this.

Looking at other trait related issues, it does sound like the might be some challenges in implementing this, is there anything in particular that would prevent this from working?

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[mxr576]

Let me copy the code snippet as an example from my issue that was flagged as duplicate of this one.

https://phpstan.org/r/465f4f45-2dc7-4406-b82c-a21926d1bdc5