T27462 Crash_on_loading_multiple_3D+t_images

Summary:
Fix for the crash caused by invalid prop assembly state due to early out.
Fixed T27462

made ShadowOutlineActor an explicit variable to avoid runtime assumptions that might break and are hard to track.

Refactoring to remove some code redundancy

+ added some constness of ImageVtkMapper::LocalStorage

access to avoid change from the outside (e.g. by PlaneGeometryDataVtkMapper3D)

Test Plan: code review and application testing (see task instructions that caused the crash)

Reviewers: O1 MITK Reviewer Group I, kislinsk

Reviewed By: O1 MITK Reviewer Group I, kislinsk

Subscribers: kislinsk

Maniphest Tasks: T27462

Differential Revision: https://phabricator.mitk.org/D345