Sidebar improvements

[nickvergessen]

Todos

• Currently the complete list is refreshed for the moderator when they change another participant => Rework right sidebar #439
• When a user is promoted/demoted by another moderator, the sidebar should rerender. => Rework right sidebar #439
• Renaming should be in the sidebar Sidebar polishing #440
• Share link should be in the sidebar Sidebar polishing #440
• Adding participants should be in the participants tab view Sidebar polishing #440
• Guests are displayed wrongly in the sidebar => Fix guest entries in sidebar #410