Feature request: Print attempt view - add a 'Print' button

[vuvanhieu143]

If you click on the print icon, you get the contents open in a plain separate tab, but it is not necessarily obvious to students that they need to Ctrl+P of using File>Print.

[vuvanhieu143]

I have implemented the code for this feature on top of the branch MOODLE_39_STABLE. You can see a diff here
#325