[AddressSanitizer] Split out memory intrinsic handling

Summary:
In both AddressSanitizer and HWAddressSanitizer, we first collect
instructions whose operands should be instrumented and memory intrinsics,
then instrument them. Both during collection and when inserting
instrumentation, they are handled separately.

Collect them separately and instrument them separately. This is a bit
more straightforward, and prepares for collecting operands instead of
instructions in a future patch.

This is patch 2/4 of a patch series:
https://reviews.llvm.org/D77616 [PATCH 1/4] [AddressSanitizer] Refactor ClDebug{Min,Max} handling
https://reviews.llvm.org/D77617 [PATCH 2/4] [AddressSanitizer] Split out memory intrinsic handling
https://reviews.llvm.org/D77618 [PATCH 3/4] [AddressSanitizer] Refactor: Permit >1 interesting operands per instruction
https://reviews.llvm.org/D77619 [PATCH 4/4] [AddressSanitizer] Instrument byval call arguments

Reviewers: kcc, glider

Reviewed By: glider

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77617