Improvements to existing features

• [Live Proctoring] Rare millisecond miscalculation in proctor online status check logic fixed
• [Live Proctoring] Better handling of proctor assignments when connectivity issues are present
• [Exam Taker] Exam Taker chat input area height now auto growing by its content
• [Back Office / API] File names in downloaded exam documents zip file now prefixed with student session ID
• [API] Prevent setting preserve to true via v3 API when exam isn't started