Clean up Classification module and plugins
Summary:
- Remove classification plugins
- Remove unused stubs and files
- Remove abandoned command-line apps
- Remove abandoned modules
- Remove Vigra as third-party dependency
- Remove broken build configurations and whitelists
Fixes T29649
Test Plan: As nothing was really altered but only removed, a successful CI build and test run should suffice.
Reviewers: floca, O1 MITK Reviewer Group I
Reviewed By: floca, O1 MITK Reviewer Group I
Maniphest Tasks: T29649
Differential Revision: https://phabricator.mitk.org/D856