Indirect instancing fixes: - Supported shaders are no longer determined at runtime, instead a list is supplied to the component on the main camera prefab. This fixes issues where instanceable objects would end up in the non-instanceable fallback renderer. - Add operations are no longer queued in order to return success/failure states immediately back to the caller. - Remove operations are now queued without relying on managed references, fixing various use-after-destroy issues. - Broadened the use of the InstanceCreationInfo struct to avoid fealing with so many function parameters. - Improved logging when instances can't be added (1) at all or (2) only in the non-instanced fallback renderer. - Fixed exceptions resulting from calling RecalculateUVDistributionMetric() after UploadMeshData()