Feature: a way to scale a Primitive2d/Primitive3d shape directly

## What problem does this solve or what need does it fill?

There should be a way to scale the size of primitive shapes after creating them. Especially for ones which take multiple elements as input (Triangle, Polygon, Polyline), scaling before creating the shape can be a bit annoying.

Usecases:
- Scaling out the shape used in a gizmo, to avoid it overlapping
- Writing out the shape in easy to reason about sizes, and later scaling them before meshing/rendering.
- When a primitive shape is created outside of my own control

## What solution would you like?

Ideally, there would be a method on all Primitive2d or Primitive3d shapes, which scales it according to what makes sense for it. For a circle, its a bit redundant as it would just multiply the radius, but for more complex shapes it quickly becomes a nice feature.

## What alternative(s) have you considered?

Scaling at some later point, maybe while rendering Gizmos. I honestly can't say i have any reason why this isn't my preferred solution, it just feels less nice.

## Additional context

None so far