Show text and media elements (aka. labels) in the course index also in non edit mode

As a user
I want to see the text and media elements in the course index
so I can understand the course structure from the course index

The text and media elements in the current version only appear in edit mode. However, the last user tests have proven that showing them also in view mode is helpful for students and teachers.

Issue background

The course index was introduced in Moodle 4.0. The decision was not to show the label activity (and any other activity without an URL) unless the teacher was in edit mode.

The reason for this decision was that labels could contain any content, and the label's activity plain text name does not necessarily be essential to comprehend the course.

However, during the last UX research about course hierarchy, most users agreed that labels are used to structure the course. Not displaying them in the index makes the course index less useful for both teachers and students. All details regarding the UX research can be found here: https://blue-hijiki-xddm.dovetailapp.com/projects/Jcf8wNf1PDE4Y9UWnTsYl/v/7iEUB5msbiaYkmljEzVTo3 

The research concludes that labels should always be visible, even when the label name is not representative of the content; for example, when there's a video on it and a generic "Text and label area" is displayed.

Once the decision is made, the technical research in MDL-77113 concludes that showing the labels in not editing mode is not only possible but easy, with the extra benefit that will simplify the current activity card template.