Generates and send a generic template.

async def _send_generic_template(self, request: Request, stack: Stack):
        """
        Generates and send a generic template.
        """

        gt = stack.get_layer(GenericTemplate)
        payload = await gt.serialize(request)

        msg = {
            'attachment': {
                'type': 'template',
                'payload': payload
            }
        }

        await self._add_qr(stack, msg, request)
        await self._send(request, msg, stack)