Required Work Group size when bigger than size_t::max?

[TApplencourt]

Look like we have 2 regime

0 < Product(size) <  max_work_group -> Fail at runtime
 numeric_limit<size_t>::<max < Product(size) -> Fail at compile time. 

Should we clarify that? Related to https://github.com/wenju-he/SYCL-CTS/blob/da719ce893298cdcbff26213606d65ca6908e1d3/tests/optional_kernel_features/kernel_features_reqd_work_group_size.cpp

Originally posted by @TApplencourt in #1010 (comment)