(cherry picked from commit 33ec8b81)

# Conflicts:
#	dmp-backend/web/src/main/java/eu/eudat/controllers/DMPs.java
#	dmp-backend/web/src/main/java/eu/eudat/logic/managers/DataManagementPlanManager.java

Merge branch 'Development' of https://gitlab.eudat.eu/dmp/OpenAIRE-EUDAT-DMP-service-pilot into Development

(cherry picked from commit d3915e26)

When generating DOI it will remain unpublished until the DMP got published, add reference identifier to the DMP (public overview) and add collaborators (associated users and researchers) to DOI generation (ref #257)

The invite pop up will show only user collaborating with DMP that the current user also is collaborating (ref #258)

Re organize DMP controller and manager functions and added the ability to add custom organization (not configurable yet) (ref #255)