[llvm] [X86][AVX512] Add pseudos for `AVX512_*_SETALLONES` (PR #169009)

[Abhishek Kaushik via llvm-commits]

abhishek-kaushik22 wrote:

> Something we're struggling with is duplicated all ones/zeros expansions for different widths, I'm worried this could make this even worse if we don't address it.

The motivation behind this patch is this crash during regalloc https://godbolt.org/z/ern6PxqKj
When we try and rematerialize `AVX2_SETALLONES` we end up with an incorrect reg class (VR256X), we can constrain the destination register in `X86InstrInfo::reMaterialize` but that seems more like a hack than fixing the root cause which is we don't have a way to set all ones vector using avx512vl.

https://github.com/llvm/llvm-project/pull/169009