Make upstream callers respect "active bindings" when querying Almanac

Summary: Ref T13641. Make "active bindings" a real query and make callers that only care about active bindings only query for active bindings.

Test Plan:

• Queried for "bindings" and "activeBindings" via Conduit.
• Disabled/enabled devices, saw binding status update in UI.
• Loaded Diffusion cluster layout.
• Grepped for needBindings(), getActiveBindings(), etc.

Subscribers: yelirekim, PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13641

Differential Revision: https://secure.phabricator.com/D21628