Display the number of change requests in the "Change Request" tab of the page extra area

I’d probably lean towards showing the total number of CRs on that page. No matter what state the CR is in (draft, published, closed, ready for review, etc.), it still shows up in the CR tab. So if the tab said “Change requests (0)”, but I clicked on it and saw two CRs: for example one in draft and one published, I’d probably think the “(0)” is a bug.

OTOH, as a user, what I’d actually care about is whether there are any open CRs (draft or ready for review). So seeing “(0)” and knowing that means there are no open CRs would be useful, since I wouldn’t have to open the tab just to check.