Upgrade to PyCSW 3

[mattiagiupponi]

The upgrade to PyCSW 3 will bring several benefits and a refactored PyCSW implementation that improves performance and security.

The primary features brought by the new version are:

• support for ISO 19115-3 (still in progress)
• more flexibility in Repository configuration/mapping*
• else?

Outside the features leveraged by GeoNode, PyCSW 3 implements the OGC API - Records protocol, which could be useful in the future.

*At the moment we have the GeoNodeRepository which uses the ResourceBase model as a metadata source. In the future, the source will come from different sources, represented by a dynamic metadata metamodel. It's not clear if the improvements to the PyCSW 3 repo configuration (e.g. support for DB Views) offer more options compared to PyCSW 2.

CC: #9147