renderIcon
Renders a 64x64 inventory icon for a Java 3D item model and writes it to outputPng. Returns true on success; false if the model can't be rendered (caller should fall back to writeMissingPlaceholder).
Parameters
resolvedModel
parsed merged JSON of the model (parent chain already resolved)
mergedJavaPack
root of the merged Java pack (for texture resolution)
outputPng
destination PNG file