Restrict input of documentation generation to header files

Summary:

• Remove dangling CMake code for old BlueBerry documentation
• Restrict input of documentation generation to header files

• Also sneaks in minor fixes in Movie Maker and Properties documentation. :-)

Fix T27624

Test Plan: I was able to successfully build the doc target in Visual Studio but we also need to manually build it on our other supported platforms.

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

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

Subscribers: floca

Maniphest Tasks: T27624

Differential Revision: https://phabricator.mitk.org/D406