Implement web-map-links extension FeatureServer link

[smohiudd]

Description

The pyarc2stac library supports ArcGIS FeatureServer datasets by adding FeatureServer layers in the links array:

"links": [
    {
      "href": "https://service.arcgis.com/arcgis/rest/datast/FeatureServer",
      "rel": "featureserver",
      "title": "ArcGIS FeatureServer",
      "type": "application/json",
      "featureserver:layers": {
        "0": "streets"
      }
    }
  ]

This was proposed in the web-map-links STAC extension. The PR needs to be reviewed and fixed to pass tests so it can be merged and included in the extension. We may also need to confirm with the extension maintainer if there is any feedback on our approach.

Acceptance Critiera

• FeatureSever layers is included in web-map-links extension.

[smohiudd]

stac-extensions/web-map-links#27