Create RB.Admin.PageView and update existing admin views to extend it

Review Request #10978 — Created March 27, 2020 and submitted — Latest diff uploaded

Information

Review Board
master
4a1431f...

Reviewers

This review request creates RB.Admin.PageView, a new base page view that is
specific to admin views. Existing views in reviewboard/static/rb/js/admin/views
that don't extend from a specific view are updated to extend RB.Admin.PageView.
They also call the parent view's initialize and renderPage as needed. This
change will help with the implementation of the admin setup banner, which needs
to be displayed on all admin pages.

Existing unit tests all pass and a manual inspection of admin pages shows that
pages still render correctly.