Update facility details API

[dboyer]

Overview

The embedded map feature supports a contributor generating an iframe of a map showing just the facilities they have contributed as well as potentially additional fields they have added that are not visible on OAR.

For this task, add additional contributor fields to the facility details API.

Part of #317

Describe the solution you'd like

Update facility details API

• Add embed and contributor arguments (/api/facilities/{id}/?embed=1&contributor={id})
• Conditionally include extra fields, as defined by that contributor's EmbedConfig, when embed is 1, in the format:

    "id": "OAR_ID",
    "type": "Feature",
    "geometry": {
        "type": "Point",
        "coordinates": [1, 1]
    },
    "properties": {
       ...regular data,
       "contributor_fields": [
       {
            "label": "Test Field",
            "value": "1234"
        },
       ...
     ]
    }
}```