Resolve "answer statistics (logic)" 2nd

Closes #113

See merge request swtp-block-ws17/arsnova-angular-frontend!93

Resolve "content types (logic)"

Closes #111

See merge request swtp-block-ws17/arsnova-angular-frontend!92

Implement function to add Answers to ChoiceContent

Add file-private class to implement answer logic with indexes

Resolve "content types (HTML)"

Closes #110

See merge request swtp-block-ws17/arsnova-angular-frontend!89

Add route to question carousel for participant

Navigate to new content creation page when clicking on "Create new content"
Make ContentCreation component a component (not a MatDialog)
Add new routes to new pages