Transformer - Add support for ingesting by spatial source: LineageAssertions

As a GCZ Developer, I want to build ingestion support for a new Spatial Source pattern: LineageAssertions.

If GCZ user specifies LineageAssertions as a SpatialSourceID, then the GCZ Transformer should be smart enough to parse the LineageAssertions array of a record, identify the first direct lineage, and attempt to retrieve geometry from that related record so that it can spatialize the source record.

This workflow will be especially helpful for ingestion of the Document data type.