🚧(scim) add SCIM importer base mechanics

[qbey]

Purpose

This could allow a SCIM client to provision users and groups.

Proposal

• add and configure django-scim2
• check if ScimImportedUser exists when a new user logs in via OIDC and create Team (and accesses) if needed
• provision Team if at least one user exists when adding/updating ScimImportedGroup
• delete Team if ScimImportedGroup is deleted
• add attribute on Team to know whether its a "collaborative team" or a synced one? at least provide the information in the client API and the resource server API
• add tests (based on https://verify.scim.dev/ requests? what more?)
• optional: implement OIDC authentication on SCIM endpoints
• nice to have: update the Group SCIM scheme to mark displayName as required...