Deleted records in archive updates

[kueda]

Currently archive updates only change and adds observations and their associated records, which means if you delete an observation or delete a photo, those don't get removed from the archive. That might be good, but might also be bad. We should give the user the option to delete records that no longer exist on iNat.

1. Give the user the option to remove records from the update interface
2. Use https://api.inaturalist.org/v2/docs/#/Observations/get_observations_deleted to determine what observations within the search parameters have been deleted
3. Observations should get updated on iNat when associated media gets deleted, so when assessing an updated observation, if a photo (or sound) in the existing archive is not longer present in the iNat response, delete it from the existing archive

[kueda]

On further thought, the /observations/deleted endpoint only returns deleted observations by the authenticated user, so we can't really use it for anything other than personal backups. We'd need a new endpoint or a modification to that endpoint that pages over observations by everyone.