[SYCL] [E2E] Fix free funcs tests

[jchlanda]

This patch:

• enables free function tests
• re-writes them in terms of sycl::ext::oneapi::this_work_item (instead of, now deprecated, sycl::ext::oneapi::experimental::this_id and friends)
• fixes build failure caused by the removal of core_sg_supported
• removes a test from free_function_queries.cpp as it was only checking correct translation between old and new spelling of the extension

[jchlanda]

Friendly ping @slawekptak

[jchlanda]

Would you like me to do anything else for this patch @slawekp, @intel/llvm-reviewers-runtime? Thank you.

[jchlanda]

@intel/llvm-gatekeepers this should be ready to roll.

Thank you.