Add tests for LSPS5 client and service. Also tests for checking the correctness of the signing logic

Author: martinsaposnic

lightning-liquidity/tests/lsps2_integration_tests.rs

@@ -88,13 +88,15 @@ fn invoice_generation_flow() {
 		#[cfg(lsps1_service)]
 		lsps1_service_config: None,
 		lsps2_service_config: Some(lsps2_service_config),
+		lsps5_service_config: None,
 		advertise_service: true,
 	};
 
 	let lsps2_client_config = LSPS2ClientConfig::default();
 	let client_config = LiquidityClientConfig {
 		lsps1_client_config: None,
 		lsps2_client_config: Some(lsps2_client_config),
+		lsps5_client_config: None,
 	};
 
 	let (service_node, client_node) =