Display category calendar events correctly in the app

This needs to be tested in a site with MDL-60813 applied. In web as admin, create 2 new categories that are not a child of Miscellaneous. Create a course in one of them, but not in the other one. Go to calendar events and create 3 events: one per category (Miscellaneous and the new ones). Enrol a student in a course of the Miscellaneous category and also in the course you created in the step 1. In the app, login with the student from the previous step. Go to calendar and check that you can see the 2 events from the categories you have courses, but not the other one. Check that they have a "category" icon next to it. Now use the top right popover to filter by course. If MDL-60836 is applied to the site, you should only see the event from the category the course belongs to. If  MDL-60836 isn't applied, then you will always see all category events.