Sphere shape should have 1 handle more

[QbieShay]

Godot version:
3.1beta1

Issue description:
Sphere shapes are not resizable from the side: if you look at a sphere shape from the side the handle is "in the middle" of the sphere, making it completely useless.

Proposal
Add a second handle for when looking the sphere from the side. 2 handles are sufficient

[Zylann]

Perhaps there could be just one handle that's always shown on the right, adjusting from the point of view? (like OmniLights)

Note: same for CSGSphere