[Clang] Add AArch64 VCMLA LANE variants.
This patch adds the LANE variants for VCMLA on AArch64 as defined in
"Arm Neon Intrinsics Reference for ACLE Q3 2020" 
This patch also updates dup_typed to accept constant type strings directly.
Based on a patch by Tim Northover.
Reviewed By: SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D93014