Following on T5403, it would be useful when adding supplemental interface-definitions and config-mode scripts, outside of the vyos-1x build, to have tools for
(1) adding entries to the config dependency dict (stored as a JSON file)
(2) running the dependency cycle check at build time

Both are simple matters, as the cycle check requires only the dependency dict itself; the challenge is only in making the update procedure simple to use for external packages.