Improve auth_shibboleth's login form

Note: Test on Boost and Clean Setup Log in as an admin Go to Site administration / Plugins / Authentication / Manage authentication Turn the Shibboleth authentication plugin on. Open another Moodle instance that doesn't have this patch on (e.g. a Moodle 3.6 instance) and do the same setup. Let's call this MOODLE2. Test Under Common settings, set Self-registration to " Email-based self-registration ". Make sure that Guest login button is also set to " Show " Save the changes. Open an incognito browser window. Enter on your browser's address bar: http://[YOUR_MOODLE_URL]/auth/shibboleth/login.php Check the appearance of the page. Confirm that it looks way nicer and consistent with the current theme compared to the original version (e.g. on your MOODLE2 instance). Confirm the layout looks good. On Clean, the guest login section will stack underneath, this is fine. Hover on the " Moodle Administrator " link. Confirm that it points to "mailto:[ADMIN'S  EMAIL ADDRESS] " Hover on the " Shibboleth login " link. Confirm that it points to " [YOUR_MOODLE_URL] /auth/shibboleth/index.php" Click on " Log in as a guest " Confirm that you get logged in as a guest. Go back to the Shibboleth login page. Click on " Create new account " Confirm that you are redirected to the self-registration page. Go back to the Shibboleth login page. Back on the admin's browser window, disable " Self-registration ". Set the " Guest login button " also to " Hide " Set the and save the changes. Back on the incognito browser window, refresh the Shibboleth login page. Confirm that the " Create new account " button is no longer shown. Confirm that the guest log in section is also no longer shown. Without selecting anything, click on " Select " Confirm that you get a validation error " Please select the organization you are member of! " Select " Example Organization 1 " Click " Select " You'll get redirected to a page with an error. But this is okay. You need to take note of the URL of that page. On another incognito browser tab, open your MOODLE2 instance and go to the Shibboleth login form and perform the previous 3 steps. Compare the URL from the moodle instance you're testing and the URL from the MOODLE2 instance. Confirm that aside from the difference in the URLs in the " target " parameters (since they point to the Moodle instance you're testing and on MOODLE2's URL), they are basically the same. Repeat the above tests for the other 2 test options in the select box.