Update the status bar correctly

Summary:
Force a rendering update before updating the status bar.

The present comment in DisplayInteractor was describing a
required re-calculation of the plane positions, however
rendering was not being updated and not able to provide
up-to-date position calculations

Merge remote-tracking branch 'maleike/fix-status-bar-updates' into develop

The changes are transferred to the new mitkDisplayActionEventBroadcast
since this is a replacement for the removed mitkDisplayInteractor.

Test Plan:
manual test

• open MITK workbench, load an image
• move your mouse pointer to any location inside of the image and scroll a few slices
• observe how the slice number / position / index increases or decreases, depending on the scroll direction
• at one point stop scrolling and scroll exactly one step in the other direction
• observe how the slice number / position / index still increases / decreases instead of going in the other direction

Reviewers: kislinsk, O1 MITK Reviewer Group I, floca

Reviewed By: kislinsk, O1 MITK Reviewer Group I, floca

Subscribers: maleike, floca, kalali, kislinsk

Maniphest Tasks: T29219

Differential Revision: https://phabricator.mitk.org/D715