Use prefix all path in RestProxy with value from backend configuration
Add questionVariant to Question model's fields

fixes #10435
Merge remote-tracking branch 'origin/master' into customization
Do not switch view when a redirect to a external login page is performed
Fix QR login, add debug logging for login
Fix and simplify QR login code
Replaced online ping by WebSocket solution
Assign WebSocket session id to user session id on login
Use WebSocket implementation for feedback posting
Update Socket.IO library
Replace session count implementation with Socket.IO implementation
Remove session activity task code