Draft: Mqtt logging

current state of mqtt logging.

The idea / workflow:

• logging is done via logging module as always (e.g. logging.info("some message"))
• a special logging-handler [1] is attached to the root logger. The handler sends a mqtt message containing the log message and some meta information
• a new dispatcher handler [2] receives the mqtt log messages and re-publish them to a thing specific topic
• the thing specific topic is determined from the thing_id, which is send in the meta information. if no thing_id is present, the message is not re-published.
• the thing specific topic is accessible (read-only?) with the mqtt credentials created in the the frontend

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[1] see https://codebase.helmholtz.cloud/ufz-tsm/tsm-dispatcher/-/blob/mqtt_logging/src/mqtt_logging.py

[2] see https://codebase.helmholtz.cloud/ufz-tsm/tsm-dispatcher/-/blob/mqtt_logging/src/LogMessageHandler.py