Admin settings FAB

[kulmann]

Initial Checklist

• I understand this is a user story and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

User Story

As a user, I want to find the actions for creating something in the admin-settings app in a well known location, so that I always know where to look for it.

User Value

Consistency

Acceptance Criteria

• Create a FAB in the admin-settings app like in the files app:
  • top of left sidebar for desktop
  • floating over main views in lower right corner on mobile
• If the current view doesn't allow to create an entity:
  • disable the FAB on desktop
  • hide the FAB on mobile
• For the views "Users", "Groups" and "Spaces", use the FAB instead of the respective "+ New" button above the entity lists for creating new entities of the respective view.