[llvm] [SelectionDAG] Use unaligned store/load to move AVX registers onto stack for `insertelement` (PR #82130)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> We have about 10 Aarch64 Unit tests failing, all of them due to the following assertion failure:
> 
> ```
> AArch64Tests: /home/nirhar/Documents/OpenSource/llvm/llvm-project/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h:576: void llvm::LegalizeRuleSet::aliasTo(unsigned int): Assertion `Rules.empty() && "Aliasing will discard rules"' failed.


This will be unrelated to this patch 


https://github.com/llvm/llvm-project/pull/82130