Pictures in altinn studio cant be closed (must step back)

### Description of the bug

When a picture is opened in altinn studio for example https://docs.altinn.studio/nb/app/app-dev-course/modul1/ if you click on the picture for the example solution. You open the picture in a bigger format. one would expect to be able to close the picture by eiteher pressing escape or by clicking the modalcover, a closebutton or backspace but only the stepbackbutton works.

### Steps To Reproduce

1. Go to https://docs.altinn.studio/nb/app/app-dev-course/modul1/,
2. Open the picture in the solution of the assignment
3. Try to close it either with clicking modalpage-cover, escape or backspace.

### Additional Information

_No response_

Start by opening the linked App development course page and reproducing the image modal behavior from the solution example. Trace the page's modal implementation and verify that clicking the modal cover, pressing Escape, and pressing Backspace all close the picture, in addition to the existing step-back control.

Written by the indexing model from the issue text.