After ca53080e added Return key handling to the "Delete route" dialog, only
the "Load no-go areas" and "Load track as route" dialogs were still missing
similar functionality.
The implementation is based on 2a431932.
Test Plan:
- Open "Load no-go areas" or "Load track as route" dialog.
- Press Space or Return to open file dialog, choose file,
Tab out of file input and press Return to confirm modal.
- Notice not having to Tab to the respective confirmation button.
eb8a7a9d36