setup spatial `feature/` endpoint

[bbest]

To pass the spatial information to the API for summarizing the data withou the detail of the spatial WKT, set up a new spatial features service similar to mregions but with our own unique layers and identifier system.

[bbest]

Perhaps with RESTful URL format:

• API internal: feature/{layer}/{fld}/{value}
  • feature/{layer}: show summary of fields and values (a la skimr table output)
  • feature/{layer}/{fld}: list all possible values and perhaps other features like size, centroid
  • feature/{layer}/{fld}: return spatial description as WKT, WKB or GeoJSON; or use as parameter for internal use of
• tile / feature server with CQL: /{layer}?filter={fld}='{value}', eg tile.calcofi.io/public.aoi_fed_sanctuaries.html?filter=nms='CINMS'