include configurable summaries in collection response #683
Description
in the STAC collection response, the specification allows for summaries. see: https://github.com/radiantearth/stac-spec/blob/master/collection-spec/collection-spec.md#summaries.
this enhancement is to enable configuration of summaries (definition) in stac-collection-metadata.json, indicating which item properties should be included in the summaries and what type of summaries to include: range, list of distinct values, or json object with properties field that is itself a list of summaries (list/range).
in configuration, provide an option to dynamically determine the summaries per request or to pre-fetch the summary based on a schedule (similar to DCAT process).