[AArch64] Emit TBAA metadata for SVE load/store intrinsics

In Clang we can attach TBAA metadata based on the load/store intrinsics
based on the operation's element type.

This also contains changes to InstCombine where the AArch64-specific
intrinsics are transformed into generic LLVM load/store operations,
to ensure that all metadata is transferred to the new instruction.

There will be some further work after this patch to also emit TBAA
metadata for SVE's gather/scatter- and struct load/store intrinsics.

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D119319