~~Other validation stuff I plan to send as soon as !450 and !550 are in.~~
~~I guess the CI is going to timeout because of too many commits, so I'll preemptively stop it.~~
-- v8: vkd3d-shader/ir: Validate PHI instructions. vkd3d-shader/ir: Do not allow IMMCONST and IMMCONST64 as destination registers. vkd3d-shader/ir: Refactor register-type-specific code in parameter validation. vkd3d-shader/ir: Check that all instructions appear in a block.