Wrong names for `LightVisibility` and `CubeVisbility`

[javagl]

The LightVisibility and CubeVisibility assets have a wrong name entry in their metadata.json.

• The name of LightVisibility is "Light Visiblity test for KHR_node_visibility"
• The name of CubeVisibility is "Cube Visiblity test for KHR_node_visibility"

The name must be the ~"actual/general/global name" of that asset, verbatim, i.e. it must only be "LightVisibility" and "CubeVisibility", respectively.

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@aaronfranke This slipped though during the review of #235 because

1. it is not documented(!) and
2. the effect (i.e. the resulting issue) is not obvious

I also didn't have on the radar that deviating from this rule would break downstream pipelines - maybe because there haven't been downstream pipelines until recently. But I just noticed that https://github.khronos.org/glTF-Assets/ chokes on these assets:

This moves the task to straighten out and update the submission guidelines (c.f. #39 ) a bit higher on my TODO list. (I already started doing things like #254 , but will have to dive deeper into that PHP script first...)

[javagl]

Fixed as of #262 (other cleanups, e.g. adding some better documentation to the submission guidelines, are independent of this specific issue)