Add and fix test files for all components and do some cleanup

Add and fix test files for all components.

Some minor refactorings are necessary for this:

• Do some minor refactoring for use of ActivatedRoute.
• Use seperate class for error state matcher FormErrorStateMatcher since declaration in RegisterComponent lead to circular dependency
• Remove unused dependencies and imports
• Fix naming of participants wordcloud component
• Fix a condition in control bar component and make some minor refactoring in nav bar component
• Move PublishContentComponent to creator module
• Delete unused bonus token components
• Delete unused RoomNotFoundComponent
• Rename AdvancedSnackBarComponent

Closes #828 (closed)