Feature Create New file

Divided the ListView operations as ViewOperations, and applied inheretence to ListView and DetailedView.
Moved rename item validation to BaseItem class.
Removed not required imports in some classes.
Implemented the create file operations and added the F7 hotkey and "New
file - F7" button, to call the new create file method.
Still missing the tests.
Remember to put the constants outside any method, make them part of the class