FindUsernameScreenVM constructor Null safety

1. farmershands
2. find_username_screen_vm
3. FindUsernameScreenVM
4. FindUsernameScreenVM constructor

FindUsernameScreenVM class

1. Constructors
2. FindUsernameScreenVM
3. Properties
4. confirmController
5. hashCode
6. runtimeType
7. Methods
8. noSuchMethod
9. onTapConfirm
10. toString
11. Operators
12. operator ==