Refactor QmitkStepperAdapter

Summary:
Remove unused parameter

Clean class and replace the custom event listener

A SimpleMemberCommand can be used instead to make the code simpler.
Additionally the setter has been moved to the class implementation.
Unused class members have been removed.

Test Plan:

• test navigation inside StdDisplay
• observe crosshair movement and image navigator
  • scroll, move slider

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

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

Subscribers: floca, kalali, kislinsk

Maniphest Tasks: T29289

Differential Revision: https://phabricator.mitk.org/D720