Move fog component to the environment settings

[keianhzo]

After the latest AFrame refactor fog is now part of the environment settings. We need to refactor this otherwise all the scenes exported from Blender with fog will be broken.

Related Hubs-Foundation/hubs#5438

[netpro2k]

Note that the current fog component is still working in Hubs its just being handled differently than before. Since we removed the fog component from aframe I merged it into environment-settings on the Hubs side but still not sure that is the best thing to do. I was looking to fix the regression quickly and this decision doesn't bind us to any changes since the external API didn't change yet. I think its probably correct to bundle it into environment-settings but we should think about it a bit more.

[keianhzo]

Oh yep, that's true. There is no urgency then in moving this to the environment settings