Recover site URL upon installation using Google Play referrer API

This issue needs to be tested in Android only. It will be nice if it can be tested in a new Android device (11+) and an old Android device (5-7). It's possible that the Google account used in Google Play needs to be registered in the beta program, I'm not sure about that. In an Android device, make sure that the Moodle app is not installed and close the Google Play app if it's open (just to be sure). Open this link in the device (e.g. you can open it in Chrome, or click it in an email, Telegram message, etc.): https://play.google.com/store/apps/details?id=com.moodle.moodlemobile&referrer=siteurl%3Dhttps%3A%2F%2Fmoodle.org%2F Google Play should open with the Moodle app page. Do NOT click the install button. Download the Moodle app apk from our deployer (if you haven't download it already) and install it. Do NOT open the app after installing it. Go back to Google Play, it should display "Open" and "Uninstall" buttons instead of the Install button. Click Open. Check that, after starting, the app automatically redirects you to the page where you enter username and password and it uses the URL https://moodle.org/ . Go back to previous page. Check that the URL field has been filled automatically with https://moodle.org/. Restart the app. Check that now the URL hasn't been filled automatically, the app only uses it once.