Rename "/judging" endpoint to "/judged"

This is to make room for a new "/judging" endpoint to capture the
notification that a player is in the process of performing judging,
(that they've started clicking on some of the words in the list).

This commit also fixes the test suite to track this change.

Note: "judged" isn't really a perfect name here. By analogy with
"answer" what we want here is a noun, which would imply "judgment" but
that suggests an entirely different meaning to my ears. So, for now,
we're going with the slightly inconsistent "judged".