Regression: SAM-2904 was partially reverted in 11.x

SAM-2904 introduced improvements to the landing page of Samigo for students. Instead of showing them empty, useless tables if there are no assessments to take, and/or they haven't made any submissions to assessments, simply provide a meaningful message to the user indicating the situation. There's no point in showing them table headers for an empty table they can't do anything with.

SAM-2904 was first merged to master (f09e9089), then merged to 11.x (41311008). However, the logic in the JSP file has since been removed in the 11.x branch. The strange part is, according to the Git log and Git blame, there is no revision on the JSP file (in 11.x) after the merge to 11.x (41311008). However upon simple inspection of the markup in the JSP (in 11.x), you can clearly see that the pieces were removed. Everything is still fine in master.

The linked PR targets 11.x exclusively and simply re-introduces the relevant code changes from SAM-2904.