nir,spirv: implement sparse images/textures

This MR only implements the SPIR-V -> NIR and NIR bits. I have this new functionality implemented with ACO, but I haven't tested it beyond reading the assembly since the functionality isn't yet implemented in RADV.

To return both a texel and residency code without allowing multiple destinations on intrinsics and texture instructions, the residency code is appended as the last component of the result. So that a 4-component texel can be returned without using a 8-component destination, this MR also allows 5-component vectors in NIR.