Update loaders to register origin_visit's state

As of today, loaders only creates origin_visit when they finish successfully (through the current occurrence_add mechanism).

This needs to be updated to:

• create one origin_visit as soon as they start (state: ongoing)
• update the origin_visit's state when done
  • successfully (state: full)
  • or not (state: partial).

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Migrated from T539 (view on Phabricator)