[Arm64] Add HVA ABI support for HW Intrinsics

[sdmaclea]

Once Short Vector ABI is supported #9599, Homogenous Short Vector Aggregates (HVA) should be supported.

One approach would be to treat these as a subclass of HFA, getHfaType() could then return TYP_SIMD8 or TYP_SIMD16. This may simplify implementation.

@CarolEidt @tannergooding @dotnet/arm64-contrib @dotnet/jit-contrib This will require a design discussion

category:reach
theme:intrinsics
skill-level:expert
cost:medium

[sdmaclea]

#9578