LwM2M Agent writes key/values to custom inventory fragment

It should be possible to configure the LwM2M agent to write LwM2M objects as key/value pairs to a custom inventory fragment.

The LwM2M agent currently stores the object and resource values in the inventory in the following format:

"c8y_Lwm2m_3303!0": {

    "5601": 11.4,

    "5602": 20.9,

    "5605": "",

    "5700": 11.7,

    "5701": "cel",

    "instance": "0",

    "operations": true

}

We would like to store it in the following format:

"my_custom_fragment_name": [
    {
         "key": "temperature",
         "value": "11.7"
    },
    {
         "key": "unit",
         "value": "cel"
    },
    ...
]

The configuration would map each resource ID to a custom name (e.g. 5700 -> "temperature").

This is similar to the feedback raised under https://cumulocityiot.ideas.aha.io/ideas/C8YCORE-I-550, but does not involve a custom decoder microservice. The LwM2M agent would do the name mapping and store the appropriate fragments in the Inventory.