Bug: Rules for publicly visible content are inconsistent

[dqnykamp]

If I create an activity in a course, and then in course navigation, highlight the activity and click "Make Publicly Available" (but don't assign it), then the activity is findable via search in Community but one gets a 404 when trying to view it.

If I then assign the activity, it is now viewable from a Community search. The funny part is that if I subsequently unassign it, the content remains viewable from Community search. Something changes when assign and the unassign, which is strange.

Further bug: if one clicks Public in the General section of Activity Controls (rather than using the menu from course navigation), then that button also assigns the activity, but without telling you that it is assigned. In fact, if one goes to the Assign section of Activity Controls, it looks like it is unassigned even though it is assigned. Reloading the page then shows that is Assigned.

A further strange part: if one does the process from the previous paragraph, and then undoes it by unassigning and unchecking Public, future clicks of Public do seem to immediately show that it is assigned in the Assign section of Activity Controls.

Clearly, there is just a bunch of confusing and inconsistent behavior. We need to rethink how Public and Assigned work together. But, in the meantime, we should at least make the behavior consistent.