[clang] [llvm] [SYCL] Add SYCL property set registry class (PR #136697)

[Justin Cai via llvm-commits]

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jzc wrote:

For now, I've placed the class in `Frontend/Offloading/Utility.h`. If we get `Frontend/Offloading/SYCL` later on then I then that would be the most appropriate place to put it. 

https://github.com/llvm/llvm-project/pull/136697