S allius/issue334 (#335)

* move forward_at_cmd_resp into InfosG3P class

- the variable is shared between the two connections
of an inverter. One is for the TSUN cloud and the
other for the device.

* use inverter class to share values between
the two protocol instances of a proxy
- move forward_at_cmd_resp into class InverterG3P
- store inverter ptr in Solarman_V5 instances
- add inverter ptr to all constructurs of protocols
- adapt doku and unit tests-
- add integration tests for AT+ commands which
  check the forwarding from and to the TSUN cloud

* adapt and improve the unit tests
- fix node_id declaration, which always has a / at
  the end. See config grammar for this rule
- set global var test to default after test run

app/tests/test_mqtt.py

@@ -47,7 +47,7 @@ def config_no_conn(test_port):
 
 @pytest.fixture
 def spy_at_cmd():
-    conn = SolarmanV5(('test.local', 1234), server_side=True, client_mode= False, ifc=AsyncIfcImpl())
+    conn = SolarmanV5(None, ('test.local', 1234), server_side=True, client_mode= False, ifc=AsyncIfcImpl())
     conn.node_id = 'inv_2/'
     with patch.object(conn, 'send_at_cmd', wraps=conn.send_at_cmd) as wrapped_conn:
         yield wrapped_conn
@@ -55,7 +55,7 @@ def spy_at_cmd():
 
 @pytest.fixture
 def spy_modbus_cmd():
-    conn = SolarmanV5(('test.local', 1234), server_side=True, client_mode= False, ifc=AsyncIfcImpl())
+    conn = SolarmanV5(None, ('test.local', 1234), server_side=True, client_mode= False, ifc=AsyncIfcImpl())
     conn.node_id = 'inv_1/'
     with patch.object(conn, 'send_modbus_cmd', wraps=conn.send_modbus_cmd) as wrapped_conn:
         yield wrapped_conn
@@ -63,7 +63,7 @@ def spy_modbus_cmd():
 
 @pytest.fixture
 def spy_modbus_cmd_client():
-    conn = SolarmanV5(('test.local', 1234), server_side=False, client_mode= False, ifc=AsyncIfcImpl())
+    conn = SolarmanV5(None, ('test.local', 1234), server_side=False, client_mode= False, ifc=AsyncIfcImpl())
     conn.node_id = 'inv_1/'
     with patch.object(conn, 'send_modbus_cmd', wraps=conn.send_modbus_cmd) as wrapped_conn:
         yield wrapped_conn