Adding event funnel extension for synchronizing during graph/relationship discovery.
Moving POM-parsing error event stuff to Tensor codebase.
Creating event to let the system respond to 404s that happen when trying to resolve files from upstream repos.
Added not-found-cache (NFC) for downloads that fail.
Added FileErrorEvent for times when a download triggers an error.
Various other code fixes in pursuit of working recursive depgraph discovery and reconnection.