[Driver] Add `-f[no-]offload-uniform-block`

By default, clang assumes HIP kernels are launched with uniform block size,
which is the case for kernels launched through triple chevron or
hipLaunchKernelGGL. Clang adds uniform-work-group-size function attribute
to HIP kernels to allow the backend to do optimizations on that.

However, in some rare cases, HIP kernels can be launched
through hipExtModuleLaunchKernel where global work size is specified,
which may result in non-uniform block size.

To be able to support non-uniform block size for HIP kernels,
an option `-f[no-]offload-uniform-block is added. This option
is generic for offloading languages. Its default value is on for
CUDA/HIP and off otherwise.

Make -cl-uniform-work-group-size an alias to -foffload-uniform-block.

Reviewed by: Siu Chi Chan, Matt Arsenault, Fangrui Song, Johannes Doerfert

Differential Revision: https://reviews.llvm.org/D155213

Fixes: SWDEV-406592