Merge pull request #14883 from sdmaclea/PR-ARM64-SIMD-misc-varTypeIsStruct

[Arm64] SIMD miscellaneous  varTypeIsStruct

diff --cc src/jit/codegencommon.cpp
Simple merge

diff --cc src/jit/compiler.h
Simple merge

diff --cc src/jit/lclvars.cpp
Simple merge

diff --cc src/jit/morph.cpp
Simple merge

diff --cc src/jit/regalloc.cpp
Simple merge