[SYCL] Generalize group_algorithm helpers

[steffenlarsen]

This commit generalizes two helper functions in group_algorithm.hpp to make it so they can also handle non-uniform groups.

[steffenlarsen]

Windows Gen12:

Failed Tests (8):
  SYCL :: Assert/assert_in_kernels_win.cpp
  SYCL :: Assert/assert_in_multiple_tus_one_ndebug_win.cpp
  SYCL :: Assert/assert_in_multiple_tus_win.cpp
  SYCL :: Assert/assert_in_one_kernel_win.cpp
  SYCL :: Assert/assert_in_simultaneous_kernels_win.cpp
  SYCL :: Assert/assert_in_simultaneously_multiple_tus.cpp
  SYCL :: Assert/assert_in_simultaneously_multiple_tus_one_ndebug.cpp
  SYCL :: Plugin/sycl-ls-unified-runtime.cpp

Reported in #12797 and #12798