To be coherent between the metadata-only deposit and the regular content deposit.
At the moment a parsed json file is added to the revision and sent to the ERMDS (Extrinsic Raw MetaData Storage).
We need to change that and send only raw input to the ERMDS.
Note that metadata can be sent in multiple deposit-request and were aggregated as a single json file.
We still want to keep the metadata as a single logical object even if we received multiple inputs.
With the XML, we need to verify if using on XML file for all XML inputs works well..
content-metadata references
https://forge.softwareheritage.org/source/swh-loader-core/browse/master/swh/loader/package/deposit/loader.py$85-87
https://forge.softwareheritage.org/source/swh-deposit/browse/master/swh/deposit/api/private/__init__.py$53-57
only-metadata references
https://forge.softwareheritage.org/source/swh-deposit/browse/master/swh/deposit/api/deposit_update.py$270-271