Allow editing end links for datafeeder

[f-necas]

With editing the frontend-config.json file in datadir for datafeeder, we can now change the links at the end of the process.

Here is the structure to add :

"links": {
    "existing" : ["geonetwork", "openlayers", "ogc-features"]
    "custom": [
      {
        "uri": "/datahub/dataset/:uuid",
        "title": {
          "default": "See data in Datahub",
          "fr": "Voir le jeu de données dans datahub"
        }
      }
    ]
}

With this example (and if data-api is set too), it will display 4 links :

• Geonetwork
• OpenLayers (geoserver)
• Ogc features (data api and if datafeeder.publishing.ogcfeatures.public-url is set in datafeeder.properties)
• Datahub (the custom one)

This work is sponsored by MEL.