Define content models

[vronk]

Implement dedicated content models for following entities

served from CMS:

• News
• Event
• Project
• Static page

served from Knowledge Base (align with the data model of the KB?)
(#5):

• Member countries
• Institutions
• Persons
• Working groups

served from external sources unified in common index (#3)

• Resources (see Implement Resource Catalogue #1)

[vronk]

definition for CMS:
https://github.com/DARIAH-ERIC/dariah-website/blob/main/lib/keystatic/collections.tsx