Refactoring to support PII changes

Move code under common/src into common/host to clear the way for other
common code under common/src (for device+host code).

Also extend ReferenceWithHistory that will be used in the next commit
for this bug.

Bug: 188792111
Test: treehugger
Change-Id: I4f3bbf5817b9cf3ad296a7716cde866857ee845f
7 files changed