Merge enums for view direction

Summary:
Replace ViewDirection and PlaneOrientation with AnatomicalPlane

Remove the ViewDirection enum from the BaseRenderer
and use the new AnatomicalPlane enum class for the
different directions / planes.
Remove the ViewDirection enum from the SliceNavigationController
and use the new AnatomicalPlane enum class for the
different directions / planes.
Remove the PlaneOrientation enum from the PlaneGeometry
and use the new AnatomicalPlane enum class for the
different orientations / planes.

Migration should be easy, since the different directions / planes /
orientations are the same and in the same order as before.
"ViewDirection::THREE_D" is now "AnatomicalPlane::Original".
"PlaneOrientation::None" is now "AnatomicalPlane::Original".

Test Plan: compile testing

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

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

Subscribers: floca, kalali, kislinsk

Tags: Breaking Change, Noteworthy

Maniphest Tasks: T26543

Differential Revision: https://phabricator.mitk.org/D753