Add own module group and migrate old menu to different modules.
This should improve user experience as most users are used to modules
and are not aware of the dropdown menu.
Rename Overview controller to Configuration controller
As it handled configurations.
This streamlines with labels and identifiers.
- Removed individual converters for TYPO3.
Conversion is now handled in a single converter.
- The new converter will import necessary dependencies upfront, e.g.
town or organisation.
- Move import state into extra class.
Relates: #34
