[clang] [Clang] Implement resource directory headers for common GPU intrinsics (PR #110179)

[Johannes Doerfert via cfe-commits]

jdoerfert wrote:

> This way the common intrinsics would be defined in a single location, and it would be harder for someone to add a new intrinsic without realizing that all files should implement a common interface.

That's one of the reasons mapping.{h,cpp} in DeviceRTL uses the extra level of indirection.

https://github.com/llvm/llvm-project/pull/110179