Always render extra menu nodes, even when logged out

Summary:
Fixes T7915. This code is a little janky, but make it work for now.

Currently, we render "extra" nodes (dropdowns, etc) only if the user is logged in.

Instead, always render them.

Test Plan:

• No more "phabricator-help-menu" error in console when logged out.
• Search selector now works when logged out.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7915

Differential Revision: https://secure.phabricator.com/D12572