Navigation within courses in the mobile app

Test on one Android and one iOS device, also tablet.

1. Enter a course and enter into any activity.
2. Check there's a navigation bar at the bottom of the screen with 2 buttons, next and previous activity (if any).
3. Navigate to the next and previous activity.
4. Special cases:
   1. Glossary and forum have splitview, test on tablet.
   2. Forum has also a + floating button, check it's correctly positioned.
   3. Try to navigate to a URL using next or previous.
   4. Try to navigate to a label using next or previous
   5. Try to navigate to a restricted activity and check it shows a preview page.
5. Open book or IMSCP and check the navigation bar at the top also changed to show navigation through chapters. (Also SCORM if enabled (SCORM debug on SCORM section).
6. Check you can use the slide bar to move around.
7. The bottom bar should disappear when scrolling down and re-appear when scrolling up

Note: The bottom and top navigation bar will be there at the same time but there's a plan to hide the bottom one by adding a previous screen.

Note 2: If any styling error occurs, please notify it carefully with the device and version of the OS.