onViewMatrixChangedObservable not firing with non-standard render loops

[PolygonalSun]

When the standard render loop is not used (eg. Only render when camera moves), onViewMatrixObservable isn't being properly fired. The suspected reason is because this observable is only fired during a getViewMatrix call. Generally, speaking, this will be called during the execution of the scene.render call. If this function isn't used, this sequence won't happen. There was a call made during a call to perform ray picking during pointer movement. With Lazy Picking, this redundancy is no longer present.

Proposed Fix: Add a call to the camera.update function when camera movement is detected.

[bghgary]

https://forum.babylonjs.com/t/on-demand-rendering-solution-broken-since-5-29/36379
https://forum.babylonjs.com/t/what-is-the-correct-way-to-render-on-demand/17256