Split apart and reorganize gizmo examples

[alice-i-cecile]

At this point I think we should break gizmos 2d_example and 3d_example in a few parts, the examples are getting pretty cramped

Originally posted by @pablo-lua in #12394 (comment)

[mgi388]

I wonder if splitting each example into 4 “quadrants” within the existing scenes would work? Eg take the 3D example now it has a camera controller. Zoomed out, if there were 4 planes and some gizmos were featured on each of the 4 planes that would probably help readability. The benefit is we don’t need to add more examples. The downside is the initial camera zoom would be further away.