[llvm] [VFABI] Move the Vector ABI demangling utility to LLVMCore. (PR #77513)

[Nico Weber via llvm-commits]

nico wrote:

FYI, you don't need to update the files in llvm/utils/gn/secondary. There's a bot that keeps them updated, and they're not officially supported anyways – nothing you need to worry about :)

https://github.com/llvm/llvm-project/pull/77513