Display offset in backtraces if necessary.

When moving to a proto tombstone, backtraces no longer contain
an offset when a frame is in a shared library from an apk.
Add the offset display again if needed, and add a test to
verify this behavior.

Bug: 267341682

Test: All unit tests pass.
Test: Dumped a process running through an apk to verify the offset
Test: is present.
Change-Id: Ib720ccb5bfcc8531d1e407f3d01817e8a0b9128c