Implement time limits for motions

[luisa-beerboom]

We need to implement time limits (per meeting) for different types of motions which will restrict certain meeting actions to certain time spans. These time limits will be a new backend model within the meetings: time_limit. See OpenSlides/openslides-backend#1582 to view the specifics of the new backend-side functionality

The client needs to:

• add the new can_ignore_time_stamps permission (that will be added) to the clients permission handling
• have a new view for creating/editing these time limits. It may look as follows:
  • the view is split vertically in two:
    • Left: A thin selectable list with the names of all time limits
    • Right: A detail view for the time limit that is currently selected (that functions as an edit view if the user has the perms)
  • the view could either be reached from the motion-list (since we're only restricting motions) or as part of the meeting settings (as we may want to add more options in the future, like restricting candidatures for example) => needs discussions
• restrict the buttons corresponding to the according actions, if the current time is not within any relevant time limits.
  • unless there are no relevant time limits (then the default case should be what we currently do for that action)
  • or unless the operator has can_ignore_time_stamps
• possibly implement notifications concerning time limits that have recently started/will end soon (the latter possibly with a countdown)
  • could be done using the banner
• the view should at least be visible to anyone who is affected by any of the time limits (although they should not be able to edit) -> autoupdate restrictions should be extremely loose => needs discussion

[luisa-beerboom]

We could additionally show the timestamp-details (something like <name>: <begin>-<end>) as a sort of calendar in the meeting start page (as a thin list on the right side or smth)

[luisa-beerboom]

The edit view for this can use the new daterange-picker that was implemented in #2361