Meadow.Cloud - Commands (MQTT messages) are not guaranteed to arrive

[alexischr]

Describe the bug
In practice, Meadow.Cloud cloud-to-device commands (OTA, 'Command & Control') are evident to not be guaranteed to arrive.

To Reproduce
Steps to reproduce the behavior:

1. Deploy a Meadow.Cloud-enabled app, such as Cultivar, configured to a network you can easily disable (I like using the iPhone's Personal Hotspot in Compatibility Mode)
2. While device is operating normally, confirm that OTA/C&C work for your app by sending a request and watching it go through
3. Disable the network
4. Send another OTA/C&C command
5. Enable the network and allow time for the device to fully reconnect to it and Meadow.Cloud/MQTT
6. Observe that the command (which is the payload of a missing MQTT message under the hood) never arrives.

Expected behavior
The user's command should execute shortly after the network is brought back up.