mitkImageDataItem: changed data type of size member to increase possible image size. Test added
Summary: Merge branch 'T24716-imageDataItem-limit-expanded' fixes T24716
Test Plan: execute mitkImageDataItem-Test
Reviewers: kislinsk, O1 MITK Core
Reviewed By: kislinsk, O1 MITK Core
Maniphest Tasks: T24716
Differential Revision: https://phabricator.mitk.org/D127