update EDR and Maps to support MetOcean access and visualization workflows

[tomkralidis]

As part of this past week's code sprint in support of the WMO Met Data Exchange Interoperability Experiment, the following updates are needed for NWP data access and visualization:

OGC API - Common

• add EDR as a provider type to feed /collections/{collectionId}/schema responses

OGC API - Environmental Data Retrieval

• update data query response JSON media types to CoverageJSON
• fix EDR base class method for instances (-> get_instances)
• fix EDR single instance handling (boolean checks)
• add support for additional .../corridor parameters

OGC API - Maps

• add subset= support (similar to OGC API - Coverages)
• add properties= support (similar to OGC API - Coverages)

Xarray provider

• add support for consolidated and squeeze options in provider config