The goal is to add a behat test to verify users can use files from Wikimedia

QA test to be automated: MDLQA-1459

QA testing instructions

1. Log in as a student and go to Settings > My profile settings > Edit profile.
2. Upload a new user picture by clicking the 'Choose a file' button.
3. Choose Wikimedia in the file picker.
4. Search for and select an image, then click the 'Update profile' button.
5. Refresh the profile page (Ctrl+F5) and check that the image from Wikimedia is displayed as the profile picture.