Move selection widgets to module

Summary:
Remove selection widget and related classes from plugin

Move selection widget and related classes to module

Since the QmitkNodeSelectionPreferenceHelper currently cannot
be moved to the QtWidgets module a workaround was implemented
were only all available data storage inspectors are displayed
inside a node selection dialog. No preferred or predefined
inspectors are selected.

Test Plan: manual testing of selection widgets using the workbench

Reviewers: floca, O1 MITK Reviewer Group I, O3 MITK Reviewer Group II, kislinsk

Reviewed By: O1 MITK Reviewer Group I, O3 MITK Reviewer Group II, kislinsk

Subscribers: kislinsk, floca, kalali

Maniphest Tasks: T29027

Differential Revision: https://phabricator.mitk.org/D765