[MSL] Support sparse image residency operations in MSL 2.2

MSL 2.2 on iOS at least adds new methods for reading and sampling textures that additionally return whether or not the texture memory was resident. These correspond to `OpImageSparseXxx` in SPIR-V. It should now be possible to implement those operations.

Start by locating the MSL texture reading and sampling entry points and the handling of the SPIR-V OpImageSparseXxx operations. Compare those paths with the MSL 2.2 residency-returning methods described in the issue; done means the sparse image residency operations are supported for MSL output.

Written by the indexing model from the issue text.