[DRAFT] improve roles

Roles should be improved. So far only roles towards DA/DQ are defined
- Decision Maker
- Facilitator
- (team) Member

Other roles could include (from https://github.com/equinor/prisma-decision-web/issues/640)
> In the current version, the facilitators have special role, in particular for being the only ones who can enter a project description.
In practice, the facilitator may not write anything in Prisma and the (new) role of scribe should be distinct. However, the role of scribe is not mutually exclusive as anyone in the team could be the scribe, this role even changing from session to session.

Roles towards the ownership of the data and project haven't been yet defined.

Start by reviewing the existing DA/DQ role definitions and the related discussion in equinor/prisma-decision-web#640. Clarify the proposed scribe role and how roles relate to data and project ownership before identifying the API entry points affected. The issue is complete only when the role model and its ownership rules are defined and implemented.

Written by the indexing model from the issue text.