Simplify Gizmo code geometry generation

[mvaligursky]

Gizmo code creates a Mesh for various primitives (cylinders, boxes ..). To operate on their vertices, it extracts those from the Mesh - for example to create a collision geometry.

#6261 allows few of these steps to be avoided. A Geometry instance can be created and data extracted from it directly, without having to create a Mesh instance.