Reland "Add sanitizer metadata attributes to clang IR gen."

RE-LAND (reverts a revert):
This reverts commit 8e1f47b5.

This patch adds generation of sanitizer metadata attributes (which were
added in D126100) to the clang frontend.

We still currently generate the llvm.asan.globals that's consumed by
the IR pass, but the plan is to eventually migrate off of that onto
purely debuginfo and these IR attributes.

Reviewed By: vitalybuka, kstoimenov

Differential Revision: https://reviews.llvm.org/D126929