Update collision visibility to use collections

[monkeyman192]

As of 2.80 blender, blender scenes has a concept of a collection.
It would be good to utilise these as they have a number of useful properties: https://docs.blender.org/api/current/bpy.types.Collection.html#bpy.types.Collection
At the least collisions should be added to a Collision Collection so that we can view/hide them all in an easy manner.
Possibly we may want to make it so that all other object types also exist within a collection?