Integrate Python SWORD 2 client into invenio-swh, using CodeMeta serializer

[alexdutton]

As a result of this, it should be possible to construct a SWORD package from a deposit. Performing the deposit will be the subject of a separate issue.

This is part of Activity 1.3 in the specification document:

Using the data model mapping developed earlier, we will create a metadata serializer for the CodeMeta format. This will allow us to export a (compressed) package from InvenioRDM which is suitable for transfer via SWORDv2, or used anywhere else that an export may be used.