Feedback adjustments

[MishaHMK]

1. Reduntant attribute RequestParam(required = false) controller annotations removed
2. UpdateUserDataDto sensetive data update removed (email and password)
3. GlobalExceptionHandler repeatable code packaged to private method
4. 'helper' package merged to 'utils'
5. Data attribute removed for entities to avoid infinite 'toString()' recusion and 'equals()/hashcode()' errors
6. Now failure of Telegram Bot API connection doesnt stop the program. Before sending notifications, connection is checked (do nothing on failure) in async procees which awaits transaction to be commited before sending.
7. Docker instruction added to README

Updated project will be redeployed to AWS after final approval