pvr: Add new instruction support for un-hardcoding

Merged Simon Perretta requested to merge simon-perretta-img/mesa:dev/compiler-unhardcoding into main

Draft for now due to soft dependency on !21391 (merged)

Adds support for new instructions required to un-hardcode various non-shader programs that run on the USC.

/cc @frankbinns @CreativeCylon @MTCoster

Merge request reports