Define strings related to encoding a device message
in JSON.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

Add a general purpose JSON message encoder,
nrf_cloud_encode_message().

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

When encoding the shadow, let the caller determine if
the reported object should be included.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

Split out update function so it can be used for CoAP.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

This was incorrectly using the ++ operator when atomic_inc()
would be better.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

Modem sec tags are unsigned, so use that representation
instead of plain int.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

Uses the Zephyr coap_client library. Sends and receives
data with nRF Cloud using CBOR and sometimes JSON.

Supports most nRF Cloud services - FOTA, data messaging,
location services (cellular, Wi-Fi, A-GPS, P-GPS).

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

Document the new nrf_cloud_coap library.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>
Co-authored-by: Pekka Niskanen <pekka.niskanen@nordicsemi.no>

Implemented support for A-GPS and cellular positioning
using nRF Cloud CoAP.

Signed-off-by: Tommi Kangas <tommi.kangas@nordicsemi.no>

Added support for connecting to nRF Cloud using CoAP.

Signed-off-by: Tommi Kangas <tommi.kangas@nordicsemi.no>

Document a sample which uses nRF Cloud CoAP.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

This nRF Cloud CoAP client demonstrates using FOTA, messaging,
cellular positioning, A-GPS, and P-GPS over CoAP.

Get modem info IMEI and mfw. Init the modem, which waits for LTE
connection. Look up server IP. Init the client, including
looking up device IP with modem info.

Send real cell pos parameters, receive, decode, and display
location. Send cell pos back as fake GNSS PVT data.

Send fake temperature sensor data. Receive and process
MODEM and APP FOTA types.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>

WIP.

Signed-off-by: Pete Skeggs <peter.skeggs@nordicsemi.no>