[clang] [HLSL] Add CustomTypeChecking and improve sema for texture builtins (PR #221060)

[Finn Plummer via cfe-commits]

https://github.com/inbelic approved this pull request.

LGTM.

Side-note from the pr description example that is not in the scope of this pr, but shouldn't we expect the caret in the diagnostic to be pointing at the applicable parameter? Right now it is just pointing at the built-in call

https://github.com/llvm/llvm-project/pull/221060