[clang] [NFC][Clang][AArch64]Refactor implementation of Neon vectors MFloat8… (PR #114804)

[Paul Walker via cfe-commits]

paulwalker-arm wrote:

Thanks @CarolineConcatto this is structurally more what I had in mind.  The non-fp8 neon types make use of general vector support within clang but the fp8 based types are completely target specific and so I'd rather keep their spread within common code to a minimum.  NeonEmitter being target specific means we have no such worries and can freely embed fp8 type support within it as you're now doing.

https://github.com/llvm/llvm-project/pull/114804