[UR] CTS tests for command-buffer native append (#17494)
The merged PR https://github.com/intel/llvm/pull/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 PR adds UR CTS testing for `urCommandBufferAppendNativeCommandExp`
for all of the L0, CUDA, HIP, and OpenCL adapters.
Resolves https://github.com/intel/llvm/issues/17448
