Auto merge of #144543 - scottmcm:more-sroa, r=cjgillot

Allow more MIR SROA

This removes some guards on SROA that are no longer needed:
- With rust-lang/compiler-team#838 it no longer needs to check for SIMD
- With rust-lang/compiler-team#807 it no longer needs to check for niches
  - This means that `Wrapper(char)` and `Pin<&mut T>` can get SRoA'd now, where previously they weren't because the check was banning SRaA for anything with a niche -- not just things with `#[rustc_layout_scalar_valid_range_*]`.
  - Technically rust-lang/rust#133652 isn't complete yet, but `NonZero` and `NonNull` have already moved over, so this is fine.  At worst this will mean that LLVM gets less `!range` metadata on something that wasn't already fixed by rust-lang/rust#133651 or rust-lang/rust#135236, but that's still sound, and unblocking general SRoA is worth that tradeoff.

Author: bors