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.
Provide first basic import mechanism.
It already allows to import entities into TYPO3 database.
Three entities are supported.
Entities are configured through import configuration.
This can be created, viewed, and edited through backend module.
Imports are tracked and accessible from backend module.
Still this is basic.
Importing lists of entities is not supported.
Multiple languages is not supported, etc.
Relates: #8214
