Summary:
@public

Moving all native methods in a single class provides the benefit of not having to load native bindings eagerly when just creating config objects in the startup paths, or setting Java-only values on them.
Loading native bindings triggers additional class loads (`YogaConfig` / `YogaNode`), and can lead to problems in multi-dex scenarions.

Reviewed By: pasqualeanatriello

Differential Revision: D14560658

fbshipit-source-id: 14e31e3c3b560675b5a752a38ae75ab80a565ea1