gallium: implement GL_CLAMP emulation

This series implements various pipe caps and hooks which enable zink to transparently handle GL_CLAMP as well as some other Vulkan/GL mismatches.

Other drivers which can't natively handle this type of wrapping will likely want to investigate enabling the clamp cap here and adding the hook, which should allow the complete removal of all the various per-driver emulation codes.

There's still some very minor tweaks on the zink side to be made for ultimate correctness, but that will follow in another series.