redesign the "data"-collection and adapt wis2box-stack, to support new version of bufr2geojson

[maaikelimper]

Investigation into #783 leads me to conclude that we need to move to a new version of bufr2geojson as Dave as made various fixes.

We need to adapt to this new version of the wis2box-stack :

• - update the oaproc to extract relevant fields for publishing using new bufr2geojson
• - update code in backend/elastic.py to create an "observation"-collection
• - adapts clients of oaproc to use the new structure where required, wis2box-webapp and wis2box-ui

[maaikelimper]

Observation-collection to hold a subset of data returned by bufr2geojson, for example:

"properties": {
        "host": "0-20000-0-60355",
        "observedProperty": "air_temperature (minimum value)",
        "phenomenonTime": "2024-11-01T07:00:01Z/2024-11-02T07:00:01Z",
        "result": {
            "value": 0.6,
            "units": "Celsius",
            "standardUncertainty": null
        }
 }