Azure Device Update for IoT Hub support

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Device Update for IoT Hub is in public preview: https://techcommunity.microsoft.com/t5/internet-of-things/streamline-device-management-with-device-update-for-iot-hub-now/ba-p/2167663

• The implementation relies on the devices implementing Azure IoT PnP, which is currently not implemented in nRF Connect v1.5.
• It enables to roll out updates to multiple devices in groups, which is an important feature for fleet management.
• Developer guide: https://docs.microsoft.com/en-us/azure/iot-pnp/concepts-developer-guide-device?pivots=programming-language-ansi-c
• Model definition needs to be published here: https://github.com/Azure/iot-plugandplay-models
• Only public model IDs are allowed: https://docs.microsoft.com/en-us/azure/iot-pnp/concepts-modeling-guide#model-ids
• IoT Hub needs to be S1 scale tier (NOK 220.83 / IoT Hub Unit) for support of Azure IoT Device Update
• Right now the ARM templates for IoT hub do not contain the configured Device Update, and everytime the solution is updated, Device Update needs to be reconnected.
• How to set up an Azure Device Update for IoT instance: https://docs.microsoft.com/en-us/azure/iot-hub-device-update/create-device-update-account

[coderbyheart]

The simulator now implements a model, which is technically nothing more than:

• announcing the modelId in the connection string
• setting the propery in the shadow

This then allows the Azure IoT Explorer to show the data in a UI:

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Only public model IDs are allowed: https://docs.microsoft.com/en-us/azure/iot-pnp/concepts-modeling-guide#model-ids

Actually, the IoT Explorer also supports other sources:

[coderbyheart]

Finally managed to create a FOTA job. The device receives this Twin update:

{
  "azureDeviceUpdateAgent": {
    "__t": "c",
    "service": {
      "action": 0,
      "updateManifest": "<same as the updatemanifest.json as string>",
      "updateManifestSignature": "eyJhbGc ... // see https://docs.microsoft.com/en-us/azure/iot-hub-device-update/device-update-security",
      "fileUrls": {
        "00000": "Public HTTP (non-S) URL to file: http://fota--devtrackeradu.b.nlu.dl.adu.microsoft.com/northeurope/FOTA--devtrackeradu/c6f6xxxx/update.hex"
      }
    }
  },
  "$version": 2
}