Only render visible forms

Review Request #8726 — Created Feb. 8, 2017 and submitted — Latest diff uploaded

Information

Djblets
release-0.8.x

Reviewers

When rending a ConfigPagesView, we check for page visibility but we
never check for form visibility. This would lead to supposedly not
visible forms being rendered, but only if there was another form on the
page was visible. Presumably this wasn't caught earlier due to Review
Board only having one form per page.

Ran unit tests.