Add a project catalog

[frafra]

The idea is to replace prosjekt-oversikt and implement it in the main catalog, by having a project catalog.

There is a main security issue for that: the NINA catalog run externally, but the project catalog could contain sensitive information that are not relevant for the external public, and we cannot connect to intern resources either (by default). It would be safer to have an internal service with some minimal integration to the NINA catalog, like a custom service which just exposes a JSON containing a list of projects' details that do not pose any security risk.

Possible roadmap:

• Create a new Django app
• Implement a model based on nina_project.yaml
• Harvest projects from NINA: read from prosjektApi service, which implements a subset of CKAN APIs on top of NINA internal services
• Create a view for browsing
• Handle permission: only project leader can add metadata to their project, while NINA users can only browse them; harvested metadata are always read-only
• Import existing additional metadata from the old catalog

In addition to reimplementing the current projects catalog within the new platform, we aim to:

• Connect resources to NINA projects: datasets, maps, portals, group of maps?

topics.txt contains a list of validated terms, which would be better handled as a custom vocabulary.