Add an "Advanced/Developer..." action item for viewing object handle details and hovercards

Summary:
Ref T13442. Ref T13157. There's a secret URI to look at an object's hovercard in a standalone view, but it's hard to remember and impossible to discover.

In developer mode, add an action to "View Hovercard". Also add "View Handle", which primarily shows the object PHID.

Test Plan: Viewed some objects, saw "Advanced/Developer...". Used "View Hovercard" to view hovercards and "View Handle" to view handles.

Maniphest Tasks: T13442, T13157

Differential Revision: https://secure.phabricator.com/D20887