This reimplements @theoryshaw 's commit 9adbd4 but has a few upgrades:
- Considers all parent / child relationships, not just aggregates
- Puts business logic in core where it belongs and tool code in tool
- Uses existing utils where possible like get_decomposition
- Does not use name based collection checking which is fragile
- Reuses tool.Collector
- Makes container assignment handle the API's capability to do things
in bulk instead of one by one in a loop, so it's faster
- Tests