add PropertiesBased DataBroker interface

Basically override "store" and "fetch" with Properties-based ones. Deprecate the file-based ones

Start by locating the DataBroker interface and its store and fetch methods, then inspect how the current file-based variants are used. Clarify the Properties-based behavior and deprecation scope, and verify the affected callers and tests cover the intended interface changes.

Written by the indexing model from the issue text.