[llvm] [AArch64] Make use of byte FPR stores for bytes extracted from vectors (PR #134117)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> It might be easier if the generalization of the fold was a separate patch (and this PR lands the previous byte store combine). That way, the test changes due to changing the non-i8 fold would be in their own patch. WDYT?

It's not worth it.  If we'd come to this design earlier we would have just landed support for all types anyway.

https://github.com/llvm/llvm-project/pull/134117