Add option to automatically load transitive dependencies

Transferred from internal JIRA issue originally created 2024-06-24.

Technically, SUSHI should load transitive dependencies so that all references from a dependency are complete. As it is now, users have to manually add necessary transitive dependencies to their dependency list. This is not ideal.

See: https://chat.fhir.org/#narrow/stream/215610-shorthand/topic/dependency.20resolving.20recursive/near/406283949

Note that at the time of opening this issue, there is a large refactor in process for FPL. This task should not be started until that refactor is completed.