Add a 'confirmed' flag to related works

[briri]

We need to add a confirmed boolean flag to the dmproadmap_related_identifiers entries on the DMP ID metadata. This should default to 'true' when creating the DMP ID and 'false' when added by other sources.

We should not send unconfirmed identifiers to DataCite/EZID.

[briri]

Using assertions block instead

"dmphub_assertions": [ { "id": "ABCD1234", "provenance": "dmphub", "timestamp": "2023-07-13T09:25:23+07:00", "note": "data received from the NIH API", "assertions": { "contact": { "name": "Donald Duck" }, "contributor": [ { "name": "Mickey Mouse", "role": ["Investigation"] } ], "project": [ { "start": "2024-01-01T00:00:00+07:00", "end": "2025-12-31T23:59:59+07:00" } ], "funding": [ { "funder_id": { "identifier": "https://doi.org/10.13039/501100001807", "type": "fundref" }, "funding_status": "granted", "grant_id": { "identifier": "2019/22702-3", "type": "other" } } ] } } ],