R1:ce887d55c2e5

Use JS to manage dashboard tab panels

Summary: Fixes T5271. This is mostly similar to normal tab panel JS, but I think we'll eventually do async rendering and/or saved tabs so it's reasonable to split it out.

Test Plan: Toggled tabs on a tab panel, saw tab selected state change.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5271

Differential Revision: https://secure.phabricator.com/D9478