ResourceProvider: Add support to filter ResourceSet features

[panaaj]

Background

Resources defined in the Signal K specification support only one GeoJSON feature per resource entry i.e.

• Waypoints = a single Point feature
• Routes = a single LineString feature
• Regions = a single Polygon feature

To enable the use of more than one feature per resource entry Freeboard-SK supports the use of ResourceSets.
ResourceSets employ GeoJSON FeatureCollections to allow the definition of multiple features of varied geometry types.

Issue

When providing a filter to a resource request, the operation only supports single feature resource types (e.g. waypoints, routes) so when the request is targeting a ResourceSet, it's features are not correctly processed and an empty result is returned.
e.g. /signalk/v2/api/resources/<my_resource_type>?position=[109.5711467220878,-9.33075032178624]&distance=185200

Noting that a ResourceSet is not currently part of the Signal K specification, there is an opportunity to define and formalise a JSON schema to support a resource entry containing more than one feature.

Implementation

This PR adds the necessary support to filter features in a ResourceSet and return only those that match the query based on the current ResourceSet definition.
If no features match then the ResourceSet is returned with an empty feature array.

{
    "name": "My resource Set 1",
    "description": "My set of resources.",
    "type": "ResourceSet",
    "styles": {},
    "values": {
      "type": "FeatureCollection",
      "features": []
},