Replace asycnio-paho with aiomqtt

[dvx76]

https://github.com/empicano/aiomqtt/tree/main

• asyncio-paho seems abandoned vs. aiomqtt actively developed
• seems simpler
• inspired by https://github.com/YoSmart-Inc/yolink-api/tree/main (used in HA integration)
• Don't pass in SSL Context to avoid impacting HA and other integrations (same as HA-core mqtt client)

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Not done but seems to work fine, also in HA. Public methods remain the same (connect(), subscribe(), ...)

Current status:

• Seems to work fine with cli subscribe command as well as in HA
• Need to implement _running attribute as done in https://github.com/YoSmart-Inc/yolink-api/blob/main/yolink/mqtt_client.py#L56
• Struggling to get the unit test working. With some print-debugging I believe the problem is that the test will publish the test messages to the MQTT broker before the MySkodaMqttClient is actually connected and subscribed. Possibly caused by the connect and subscribe now running in an asyncio task ?