[Feature request] Export image with its name rather than just the GLTF's name + number

[MeltyPlayer]

One small issue I've noticed with SharpGLTF is that it exports satellite images as [GLTF name]_0.png, [GLTF name]_1.png, etc. rather than using the name passed into ImageBuilder.Name. I noticed that this is because of the following line in the export logic: https://github.com/vpenades/SharpGLTF/blob/ec39f0f7fb210f45a8bb68b75d32b41998f654bf/src/SharpGLTF.Core/Schema2/Serialization.WriteSettings.cs#L389

I was hoping to request that the actual name be used instead, only falling back to the number approach if the name(s) were null.