Improve SSAO / Mirror reflections / Refractions

[sebavan]

https://forum.babylonjs.com/t/ssr-when-i-rotated-a-mesh-the-reflection-shows-wrong-and-connected-to-the-mesh/30915/17

• Refine and update our Post Processes (includes reflection/refraction/irradiance/translucency/clearcoat)
• Evaluate if they could fit in the Default Rendering Pipeline

[sebavan]

On the same topic, and to not forget let s improve not only SSR, but also the PBR mirror texture usage.

I am grouping it here due to the similarities of the issues regarding the roughness.

Let s split it when we start the work on it.

https://forum.babylonjs.com/t/reflection-probe-and-arc-camera/32468/19

[sebavan]

Also related https://forum.babylonjs.com/t/mirrortexture-for-floor-with-roughness/24057/5