Include zoom level in resource listResources requests

[KvotheBloodless]

Currently, resource requests coming in from Freeboard include the location and a distance parameter to allow resource providers to geographically select which resources to return in listResources requests. Resource providers may return multiple types of entities in the response to that single request which can result in a cluttered chart display.

If Freeboard were to specify the current zoom level as part of the query, a resource provider could decide to filter out the entities which would not be relevant at that level of zoom.

For example, at a very low zoom, we may be interested in seeing just anchorages, marinas or inlets. As we zoom in, more detailed features such as hazards, navigational aids, boat ramps, etc... become more useful.

[panaaj]

I can add %map:zoom% as a token that can be included in the Notes fetch filter in FSK settings.

This is an enhancement to the resources API OpenAPI definition to add zoom as a valid parameter so I have created an issue in the server repository for the roesource provider to be updated.

SignalK/signalk-server#1851