Add support for Adafurit I/O IoT service

[gigapod]

This is a customer request via this issue:

sparkfun/SparkFun_DataLogger#20

It would required a new driver - to generate the correct mqtt payload for Adafruit.

Unclear how popular this service is

[brentru]

@gigapod Hi - I work on this service. Please let me know if you need any assistance or would like a second look at a PR for this driver!

[gigapod]

HI @brentru -

We'll take a look at this this quarter - I expect an update to the core flux-sdk and DataLogger in a couple months, with work starting once the the RP2350 port is wrapped wound down over the next couple weeks.

Given that this is a MQTT-based service, I expect the driver should be fairly straightforward.

-Kirk

[brentru]

Sure - let me know if you need any assistance :)