Meeting: closed meetings

[MSoeb]

A new function for meetings is required that allows the meeting to be closed from the inside and NO admins other than the meeting admin have access to the meeting. Only the event admin can add new accounts to the meeting after it has been closed.

This enables the creation of closed meetings.

[Elblinator]

We need a new setting in the meeting_level:

• -> the setting should be in General -> Meeting information -> on the bottom: a checkbox with the label „Close your Meeting from the inside“
• If a meeting is locked from the inside then only users with the permission to manage settings can edit Information about the meeting (meeting information include: Meeting title, Description, Event location, Meeting date, Administrators, Tags and External ID)
• Only participants from a locked meeting can navigate into the meeting
• Everyone (who can already see these meetings) can still see the meeting in the dashboard, meeting-list and committee-detail view, but the locked meeting has a locked icon left next to the meeting name

[Elblinator]

waiting for backend Issue with the new setting: https://github.com/OpenSlides/openslides-backend/issues/2497

[Elblinator]

also waiting for https://github.com/OpenSlides/openslides-meta/issues/119