[llvm] [GIsel][AArch64] Legalize <2 x i16> for G_INSERT_VECTOR_ELT (PR #65830)

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vfdff wrote:

 

> > > Do we need to add `widenVectorEltsToVectorMinSize` to more vector operations?
> > 
> > 
> > Now only do the minimal fix type **v2s16**.
> 
> And why not do `widenVectorEltsToVectorMinSize()`?

Thanks @aemerson.  Apply your comment, refactor the widenVectorEltsToVectorMinSize to support the scalar type of **Query.Types[1]**, then pass 1 as the type index to avoid add handling for the destination type in LegalizerHelper.

https://github.com/llvm/llvm-project/pull/65830