[clang] [OpenCL] Add subgroup UI image overloads builtin functions (PR #198904)

[Sven van Haastregt via cfe-commits]

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

`OpenCLBuiltins.td` additions LGTM at a glance. As this is vendor specific I have not checked the actual builtins.

https://github.com/llvm/llvm-project/pull/198904