Add a 'testing' step to the deposit

Between the 'loading' and 'done' states of the deposits, we should add a state meaning that the deposited data is being tested. This would be done by requesting a cooking to the vault, and checking the swh-id of the result archive of the cooking is the same as the input archive.

This would provide a full check of the ingestion, guaranteeing that the input was properly saved.

Additionally, this will add the artifact to cache of the vault, allowing faster retrieval later.

Migrated from T1714 (view on Phabricator)

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