Builder refactor

I like this refactor in general, like moving something that every builder had to basically do out of the their function. But unsure on how it was done. Maybe something like the below is better, then a helper function implements the base open_system and calls the open_system_static_roles function.

struct u_builder
{
	struct xrt_builder base;

	xrt_result_t (*open_system_static_roles)(struct xrt_builder *xb,
	                                         cJSON *config,
	                                         struct xrt_prober *xp,
	                                         struct xrt_tracking_origin *origin,
	                                         struct xrt_system_devices *xsysd,
	                                         struct xrt_frame_context *xfctx,
	                                         struct u_builder_roles_helper *ubrh);
};

Thoughts greatly appreciated.