Adapt Remeshing view to new selection widgets

Summary:
Use a QmitkSingleNodeSelectionWidget instead of a QmitkDataStorageComboBox.

Ref T27594

Test Plan: Manual GUI testing

Reviewers: O3 MITK Reviewer Group II, floca

Reviewed By: O3 MITK Reviewer Group II, floca

Subscribers: floca

Maniphest Tasks: T27594

Differential Revision: https://phabricator.mitk.org/D354