[SYCL][InvokeSimd] Allow callables to return uniform (#10714)
The spec states that returning a `uniform` object is allowed:
"Return values of type sycl::ext::oneapi::experimental::uniform<T> are
not anyhow converted, and broadcast to each work-item; every work-item
in the sub-group receives the same value. NOTE:
sycl::ext::oneapi::experimental::uniform<T> return type is the way to
return a uniform value of simd or simd_mask type."
Update the compile-time error checking and ESIMD verifier to allow this.
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
