[clang] [Clang][AArch64] Add fp8 variants for untyped NEON intrinsics (PR #128019)

[Paul Walker via cfe-commits]

paulwalker-arm wrote:

> @paulwalker-arm the reasoning behind creating separate records, is that mfloat type is not available for aarch32 architectures and therefore all intrinsics using it need to be gated behind `ArchGuard = "defined(__aarch64__)"` .

I see.  How practical would it be for NEONEmitter to infer the ArchGuard based on the type? I'm assuming ArchGuard is either unset of set to what we need for all the cases we care about.  This is not a firm ask but it would be nice to reuse the existing definitions if possible.

https://github.com/llvm/llvm-project/pull/128019