Add AMDGCN option similar to `cuda-compute-capabilities`

[Thyre]

trafficstars

Summary

This PR aims to implement a similar option to cuda-compute-capabilities (and related options) for AMD GPUs. The option can then replace the manual handling done in some EasyBlocks, e.g. Clang & LLVM, allowing to enable (some) GPU builds without the need to alter the EasyConfig.

Most of the handling was copied from CUDA, while some options were skipped as they don't make much sense, e.g. cuda_cc_space_sep_no_period.

The used regex should support all GPU architectures starting from gfx600, including the more recent generic targets. Actual compiler support then needs to be present in the compiler consuming these architectures. Both GCC and LLVM accept the same naming, i.e. gfx[...], including generic targets.

---

Missing features compared to CUDA

• cuda_cache_dir option is missing. I haven't found something similar for HIP yet, but may simply have missed it
• "int only" options are missing, though hard to provide with generic targets and targets like gfx90a
  • Maybe a target without gfx?

More to be determined.

Known issues

• The regex for generic targets is not perfect, allowing e.g. gfx10--generic to pass, even though it is not allowed.

---

Resolves #4829