Support `KHR_texture_transform` in property texture properties

[j9liu]

Depends on https://github.com/CesiumGS/cesium-native/pull/822, so merge that first.

Similar to #1360 . Use https://github.com/CesiumGS/cesium/tree/main/Specs/Data/Models/glTF-2.0/PropertyTextureWithTextureTransform/glTF for this one.

Picking

• Open the 06_CesiumMetadata sample level
• Load a tileset with the aforementioned glTF in it.
• Modify the Level Blueprint to print the feature ID like so:
• Press play. If correct, the very top-left pixel should return the value 54 / 255 = 0.21176470588. The bottom-right pixel should return 135 / 255 = 0.5294117647

Styling

• Add a CesiumFeaturesMetadata component to the tileset
• Click Auto Fill. You should see a feature ID texture with the "Has Khr Texture Transform" flag = true
• Click Generate Material. There should be nodes for the scale / offset / rotation from KHR_texture_transform:
• The base color texture is also used for feature IDs, so if the texture transform works, the square should appear exactly the same. Configure the material graph to look like so.
• Create a new material instance with this as the layer (and remember to name it "FeaturesMetadata"!). Then assign it to the tileset. It should look exactly the same. You can test this by clicking the "revert" button next to the material and checking if the appearance changes.

Bonus Changes

1330 unfortunately made things complicated for the sample models used, because the base color texture and the features / metadata texture used are the same. I feel like this isn't a robust fix, but what I've done as a band-aid for the release:

• Opened https://github.com/CesiumGS/cesium-native/pull/822.
• Before FCesiumModelMetadata is created, iterate over all of the primitive's materials, and find if any of the images are used by metadata. If so, we insert a makeImageCopy = true variable in the extras.
• Before FCesiumPrimitiveFeatures is created (and before material textures are loaded), do the same thing as above.
• If this extra is present, then the TextureView will be created with a CPU copy, which avoids picking errors.

@kring I know you suggested the approach of duplicating textures in the glTF itself, but I'm hesitant to modify the glTF images itself? (maybe unjustifiably so). But let me know if what I've done is atrocious.

[kring]

@j9liu when you've addressed the minor comments here and in https://github.com/CesiumGS/cesium-native/pull/822, please go ahead and merge them yourself. That way I won't need to wait for CI before I can start the release process at the end of your day today.

[j9liu]

Thanks @kring for the review! Merging with your approval.