sycl::work_group_size_hint should be refactored #7699
Description
The sycl::reqd_work_group_size attribute was changed in #7450 to make the SYCL behavior and the non-SYCL behavior of the related attributes take different paths. As an effect, the change allows the attribute to carry a variable number of argument in the SYCL case, allowing both clang and later translations to make correct analysis of the given arguments.
Likewise sycl::work_group_size_hint should be refactored in the same fashion, splitting the SYCL and non-SYCL logic and only keep the user-specified arguments.