Add a build rule for opt-in ABI dumps

The developers can specify ref_dump_dirs for shared libraries in
Android.bp. Each of the ref_dump_dirs generates a command to diff the
ABI with the reference dumps in the directory. The existing ABI diff for
VNDK, NDK, and Mainline are not changed.

Bug: 227282691
Test: make libutils
Change-Id: I62158393c8804200e96d538bc69c24147cb5caa5