Upgrade to GN 4

[giohappy]

Upgrade the project (currently based on GN 3.2.x) to GeoNode 4.0.2. A new branch will be created to manage the upgraded project.

Documentation of the current deployment is available here.

The following must be taken into account for the upgrade:

• any customization inside the project
• backward compatibility with their Airflow service (API changes?) and QGIS plugin

[giohappy]

close in favour of https://github.com/geosolutions-it/support/issues/2611