When a user pastes a Phabricator URI into the search box, redirect to the URI

Summary:
Depends on D20509. See PHI1224. Ref T5378. With some frequency, I paste URIs into the global search input (I am dumb).

When I do this dumb thing, redirect to the URI as though the global search was a URI bar.

Maybe only I am dumb like this, but I don't think it'll hurt anything.

Test Plan: pasted a URI and hit return; tried to eat a rock

Reviewers: amckinley, joshuaspence

Reviewed By: joshuaspence

Maniphest Tasks: T5378

Differential Revision: https://secure.phabricator.com/D20510