Revise Movie Maker documentation
Summary:
- Fix the page id of the Movie Maker documentation
- Remove any references to libav from code and documentation
- Fix QWebEngine warning about unregistered qthelp scheme
- Fixes T27102
Test Plan: - Press F1 while Movie Maker view is active
Reviewers: O3 MITK Reviewer Group II, O1 MITK Reviewer Group I, nolden
Reviewed By: O3 MITK Reviewer Group II, O1 MITK Reviewer Group I, nolden
Maniphest Tasks: T27102
Differential Revision: https://phabricator.mitk.org/D362