[Utils] Deprecate safe_permute

[kylesayrs]

Background

In that past, it was noticed that value[:, perm] would throw an error for the FP8 dtype because "RuntimeError: "index_cuda" not implemented for 'Float8_e4m3fn".safe_permute was used to avoid calling index_cuda for the FP8 dtype.

However, it has been discovered that Tensor.index_select achieves the same effect without needing to call index_cuda. Tensor.index_select is superior because it supports negative values for dim, unlike safe_permute.

Purpose

• Enable group activation quantization by enabling permutations to be applied to the last dimension. safe_permute did not support negative dim values
• Remove unnecessary code (I implemented this function before I was aware that Tensor.index_select would achieve the same effect

Changes

• Deprecate safe_permute in favor of Tensor.index_select
• Updated test to also test meta device and to be easier to read

Testing

• Regression and new test passes
• Tested safe permute with torch==2.7.1 (2.7.0 is the lowest version supported by LLM Compressor and vLLM)

[shanjiaz]

Lgtm!