Investigate approaches to more natural (less frustrating) Bundle authoring

Transactional bundles use UUIDs and urn:uuid references to relate resources together in the context of a single bundle. FSH does not support a natural approach to this, but rather, authors need to brute force it. We should try to find less frustrating approaches to solving this problem here (and in other similar use cases if they exists).

See: https://chat.fhir.org/#narrow/stream/215610-shorthand/topic/example.20FSH.20Bundle.20transaction.20with.20Create.20entries/near/222754301