Add UR CTS testing for command-buffer native command

[EwanC]

The PR #16871 introduced new UR entry-points urCommandBufferAppendNativeCommandExp and urCommandBufferGetNativeHandleExp, however there was no UR CTS coverage for urCommandBufferAppendNativeCommandExp included, as verification was done via SYCL E2E testing.

This ticket is to add UR CTS testing for urCommandBufferAppendNativeCommandExp similar to that of https://github.com/intel/llvm/tree/sycl/unified-runtime/test/conformance/exp_enqueue_native for all of the L0, CUDA, HIP, and OpenCL backends.

[EwanC]

This is being done in PR #17494