Add the Animation_SamplerType model group

[stevk]

Test models for animation sampler component types.
Animation_SamplerType

Fixes #533

[stevk]

@bghgary We'll need a updated npm babylonjs package with this fix before we can generate reference screenshots for these models.

[bghgary]

@lexaknyazev For normalized non-float quaternions, it's impossible to get a perfectly unit quaternion. The validator is giving errors for BYTE (though not for SHORT), but I don't think we can make it any closer. See

glTF-Asset-Generator/Output/Positive/Animation_SamplerType/ValidatorResults/Animation_SamplerType_01.json

Line 10 in 34047f0

"messages": [

. Also, should implementations normalize quaternions when the type is normalized non-float?

[lexaknyazev]

For normalized non-float quaternions, it's impossible to get a perfectly unit quaternion

I think there was a proposal to adjust the validation threshold so that it allows the error from ubyte quaternions.