Network opportunistic physics

[mwfarb]

Capturing discussion between @johnchoi313 @mwfarb @hi-liang.

Goal: create consistent remote physics operations publishing pose.

Plan: create a remotePhysics scene-option parameter Boolean when false, by default, local physics in use by web and unity. When true, disable all local physics on all platforms and let any remote python or unity client publish pose updates from physics. Use schema established from aframe physics cannon.js to communicate physics properties of all objects on the wire.

Affects: properties of impulse, dynamic-body, static-body, scene-options

Needs:

• web-core: add remotePhysics handler. Disable pose updates for local physics when using build3d.
• python: centrally add physics like pybullet to library. Implement remotePhysics true for above Affects properties of objects and publish physics pose updates.
• unity: use unity's native phyx physics library. Implement remotePhysics true for above Affects properties of objects and publish physics pose updates. Do not publish pose updates when local physics in use, but rendering is ok.