[llvm] [AArch64] Coalesce the perfect-shuffle table (PR #202617)

[David Zbarsky via llvm-commits]

dzbarsky wrote:

> Can we move this to a .cpp file instead?

Sure, that works as well. Will revise.

> Also, I saw that you opened a lot of pull requests in a short time. Were some of these AI/LLM-assisted? If so, [you have to disclose this](https://llvm.org/docs/AIToolPolicy.html). Also, please shorten the PR descriptions and remove unnecessary information.

Thanks for the pointer, I will adjust the descriptions + add disclosures. Also just a note, I opened all of them as draft to make it easier for me to self-review, and many of them will likely need revision. Only the ones marked non-draft should be looked at by humans as something that is intended to be landed!

https://github.com/llvm/llvm-project/pull/202617