replace read-all-devices.

[alsuren]

Its different use-cases should be split into:

• a no-mqtt mode for publish-mqtt.
• an example in mijia crate that takes a bluetooth address as env var.
• an example in mijia crate that continuously scans and connects to each sensor in turn for a configurable time/reading-count.

[qwandor]

Discussed in person, the first two use-cases listed above are essentially covered by the readings. Something that handles retries and disconnecting might be useful for the third, for handling more sensors than the Bluetooth adapter supports simultaneous connections.