Add fullscreen panzoom

[hpawe01]

We want to have the option to view the different choices in a fullscreen mode where we can zoom and pan the image. If the option "enable image zooming and panning" is active, we add a small button in the upper right corner of the image. We use parts of the h5p core fullscreen logic but we couldn't use the functionality directly because here we don't want to show the whole content as fullscreen but only a specific element inside the content.