Remove duplicate iot device commands help and reformat iot messaging helps

This pr fix:

the weird formatting in Iot messaging helps
Removed duplicated helps of iot device in main help doc safely by validating they are not used anymore
Fix hub_name param help from iot hub state migrate

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[ ] If introducing new functionality or modified behavior, are they backed by unit and/or integration tests?
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Azure / azure-iot-cli-extension