Cleanup instanceof

[BenjaminDeleze]

Replace instanceof by a check with nodeType when possible because it:

• improves the performance
  | Node | Instanceof | nodeType |
  | --- | --- | --- |
  |Background| 0.06ms | 0.019 ms |
  |Shape| 0.27ms | 0.077ms |
  |Robot| 0.28ms | 0.09ms |
• moreover using instanceof was the cause of a lot of imports and we had circular dependencies errors by the past.

The only reason to still use instanceofsometimes it to check for a node and its derived ones. For example, when checking
if (node instanceof WbGroup)it checks against group, but also, pose, transform, solid, and so on.

This PR also adds support for castShadows and isPickable in WbShape that were missing.

[omichel]

Nice clean-up.