[flang][cuda] Convert gpu.launch_func to CUFLaunchClusterKernel when cluster dims are present (#113959)
Kernel launch in CUF are converted to `gpu.launch_func`. When the kernel
has `cluster_dims` specified these get carried over to the
`gpu.launch_func` operation. This patch updates the special conversion
of `gpu.launch_func` when cluster dims are present to the newly added
entry point.