feat(gizmo): custom colors for gizmos

[PhilippeMorier]

What

• support setting custom colors for hover & disable material for
  • axis-drag gizmo
  • plane-rotation gizmo
• related https://forum.babylonjs.com/t/setts-of-gizmo-color-when-events/22271

Why

• to avoid setting it via accessing "private" members
• to avoid white reflection color on manually set hover material
  

Visuals

Before PG	After

[bjsplat]

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[bjsplat]

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[RaananW]

I like the change! I will let Cedric go over it as well.

I just have a single comment about the asArray call. otherwise - make sure to run npm run format:fix to make sure your code is formatted

[bjsplat]

Visualization tests for webgl2 have failed. If some tests failed because the snapshots do not match, the report can be found at

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[CedricGuillemet]

LGTM

[Popov72]

LGTM!

If you want, you could add getters and setters for the new colors, so that they can be changed at any time.

[RaananW]

i'll merge this. @PhilippeMorier - thank you so much for your time and contribution! If you want to add the ability to change the colors in runtime (which is now possible because of the shader changes) you can submit another PR.