ChargePoint._handle_call return response

[wafa-yah]

In our app we are logging the OCPP call results:

• we are currently relying on a decorator that decorates the _on_action ChargePoint handlers.
• At the level of those handlers we do not have access to the message.unique_id which is a logging requirement, for that we decided to use ChargePoint._handle_call method.
• By doing so we lost access to the response which is also a required field for the logging.
• To resolve this, we want to make ChargePoint._handle_call has the response as return value.

So basically the following:

class ChargePoint:
    ....
    ....
    async def _handle_call(self, msg):
        ....
        ....
        return response

[wafa-yah]

Resolved: #538