[llvm] [AArch64][SVE] Add patterns for bit-select instructions. (PR #138689)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> > Note you can use these instructions for Neon modes as well https://godbolt.org/z/ccdEoE1G7
> 
> I was thinking we could add these cases in a subsequent PR, but I'm happy to do it here if others agree.

I agree it would be better for a subsequent PR to extend the fixed length support.

https://github.com/llvm/llvm-project/pull/138689