Add separate static property through trait if parent already declares it

[iluuu1994]

Closes GH-10935

https://wiki.php.net/rfc/horizontalreuse

It is almost like a language supported and failsafe copy'n'paste mechanism to build classes.

It's reasonable to expect the case with and without properties to behave equivalently.

[dstogov]

I won't object.
I see - the proposed logic works.
It looks weird, but works.

[iluuu1994]

https://externals.io/message/119809 There weren't any objections from the mailing list, so I'll merge this PR.