CB: New hook lib for Postgres
One of the early steps that will eventually lead to a functional Config Backend for PostgreSQL is to create a hook library.
The goal of this ticket is to:
- create a new hook library itself
- create stub test framework
- create stub documentation for it
- update makefiles
The changes probably should be done in a way that does not include this hook in the release code. That would come later, once the lib is somewhat functional.