Video collection: video site for public learning video offerings

With 10.5 we add the learning resource type video, see OO-725.

In many scenarios it would make sense to make the accessible to all users within the platform for self-study, independent of the courses. It is like a course catalog, but not for courses but rather for videos.

The goal of this issue is to implement a new "Video collection" site where all videos of the platform are displayed in a YouTube style interface.