Updates validator schemas to support geoJSON in the properties

[bitbeckers]

Describe the feature you'd like to request

The hypercert metadata validators should support geoJSON files in the properties

Describe the solution you'd like

Expand the schema to detect and explicitly validate geoJSON. If a link to a geoJSON was detected, the SDK should download the file and validate it's content.

Describe alternatives you've considered

Allowing for the full geoJSON to be attached to the metadata. This would make the size of the metadata unpredictable as geoJSONs can be >10MB. Which is terribel to fetching/querying hypercerts metadata (let alone on mobile)

[bitbeckers]

This has been implemented to only check on the structure of the geoJSON property and the path to the external resource declared.