[Proposal] Allow adding members to orphaned spaces using an n-key-system

There are cases when a the all space-manages of a space are unable to perform their management duties on said space (e.g. death, left company, etc).
In those cases the administrators of the instance need a way to add a new manager to the affected space. To prevent a malicious actor to grant those privileges to somebody without verification we propose to have an n-key-system, meaning that those actions need a defined number of votes to go into effect.

**Example:**

We have an orphaned spaces, usually it would fall into the responsibility of the instance admins to grant space-manager privileges to another trusted person. To avoid abuse this must not be done by only a single administrator. So the request for promoting a trusted person to space-manager for the orphaned space is created by a instance admin. n-administrators need to approve this request for the trusted person to become the new space manager.

**Technical proposal:**

- n-Users (n>1) are defined as voters for promtion requests in case of orphaned spaces
- Admin A creates the request to promote User B to space-manager
- an event is emmited which creates a modal in the user interface of the previously defined voters
- if m voters (m is a configurable quorum of voters) approve the request, User B is promoted to space admin for the orphaned spaces
- votes need to be logged into the audit service

/cc @kobergj @mmattel @micbar