Fix point light radius

[Feilkin]

Objective

Fixes #9488

Solution

Set point light radius to always be 0.0. Reading this value from glTF would require using application specific extras property.

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Changelog

Fixed

• Point Lights use Range for Radius when importing from GLTF #9488 Point Lights use Range for Radius when importing from GLTF

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Example alien_cake_addict failed to run, please try running it locally and check the result.

[DGriffin91]

I feel like this should probably have a migration guide section since it will change the way scenes look. Unfortunately since KHR_lights_punctual doesn't have radius I don't really know what the migration should look like.

[JMS55]

Approved, but needs a migration guide letting people know about the change.

[Feilkin]

Not sure what the migration guide would be, as there is now no way to achieve the previous behaviour, and the previous behaviour was also nonsensical as it would mean the point light has instant falloff from the given intensity to 0 at the radius, ie. the light source only radiates inside itself while emitting no light.

Edit: from the PR template: "Fixing behavior that was definitely a bug, rather than a questionable design choice is not a breaking change."