Redirect older "/panel/" settings URIs to modern location

Summary:
Ref T11098. We have a fair number of these, including links in email, which we can't turn into explicit /user/ URIs.

Just redirect them to the modern places.

Test Plan: Clicked "Customize Menu..." on home page.

Reviewers: chad, avivey

Reviewed By: avivey

Subscribers: avivey

Maniphest Tasks: T11098

Differential Revision: https://secure.phabricator.com/D16049