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/src/gen3plus/inverter_g3p.py

@@ -8,6 +8,15 @@ from gen3plus.solarman_emu import SolarmanEmu
 class InverterG3P(InverterBase):
     def __init__(self, reader: StreamReader, writer: StreamWriter,
                  client_mode: bool = False):
+        # shared value between both inverter connections
+        self.forward_at_cmd_resp = False
+        '''Flag if response for the last at command must be send to the cloud.
+
+           False: send result only to the MQTT broker, cause the AT+ command
+                  came from there
+           True: send response packet to the cloud, cause the AT+ command
+                 came from the cloud'''
+
         remote_prot = None
         if client_mode:
             remote_prot = SolarmanEmu