[clang] [HLSL] Finish exposing half types and intrinsics always (PR #132804)

[Chris B via cfe-commits]

llvm-beanz wrote:

> Finish the work of #81782

Maybe instead:

> Apply pattern of #81782 to intrinsics added in #95999.

Also probably worth having a description of the problem this solves in the description so that it ends up in the final commit message.

https://github.com/llvm/llvm-project/pull/132804