agx: Handle indirect textures+samplers in texture instructions
Depends on !21546 (merged).
This works for the texture instructions themselves. It's not enough for the sysvals associated with textures and samplers (notably lod bias) so it's not a complete solution. That support will come with the new sysval infrastructure in !21703 (merged) and a lower_mem_access_bit_sizes
callback. Since we're upstreaming the support in stages, we don't touch CAPs/features.txt so there's no regression