Also show responsible groups in the "visible for" list

[lukasrad02]

Is your feature request related to a problem? Please describe.

When creating an event that should be visible by groups A and B and where group A is responsible/can manage the event, group A won't be shown in the "visible for" list after saving the event. This makes sense, as managing an event should always include viewing it, but it might be confusing when groups that have been added to the "visible for" list disappear from it after saving.

Describe the solution you'd like

I'm not sure about a perfect solution, as the other way round (also showing managing groups in the "visible for" list) could also be confusing: If a group is removed from that list, but still among the managers, it will keep its view permissions, although it has been removed. Some solutions that might make sense, maybe also in combination:

• Below the "visible for" box, there is some help text saying

  [...] Unabhängig davon ist die Veranstaltung für alle Benutzer sichtbar, die sich bereits angemeldet haben.

  It would make sense to add

  [...] und alle Gruppen, die für die Veranstaltung verantwortlich sind

• When a group is added to both lists during editing, show a information sign on the group with a tooltip specifying that the group will receive the view permission automatically.

• Instead of the two separate selects, show a table of all groups with radio buttons for permissions. If a table of all groups would be to long, show an empty table with a select to add groups

Describe alternatives you've considered

see above

Additional context

none

[lukasrad02]

I've just noticed that this issue is just the opposite of #148, where you explicitly removed the responsible groups from the "visible for" list. Nevertheless, I'd suggest to at least update the help text.