Make functionality to change directory in FXFileChooser configurable

[Oliver-Loeffler]

FXFileChooser allows to change directory in different ways:

• locations menu always shows the user data folder
• locations menu may provide navigation linkts to other pre-defined locations
• opening a directory chooser using the button or menu
• manually pasting a valid directory into the search bar

There may be cases, where opening either all of these options or a subset is not permitted.
So ideally there should be a standard case and each of these options should be configurable programmatically.