CInvokeCallback internal code.
make __internal._cinvoke_callback(ctx, func, userData, retString, paramString, method): Class constructor.ctx: CInvokeContext instancefunc: CInvokeFunction instanceuserData: User dataretString: Return value type of callback.paramString: Parameters of callback.method: Kite method to call.destruct(): Free associated memory and resources.get_entrypoint(): Retrieves function pointer for callback function.