Add collections conformance

[TomAugspurger]

(hopefully this is the right place to report this)

In stac-utils/pystac-client#320, @system123 noticed that pystac-client's .get_collections() method was slow. It relies on STAC API advertising a /collections endpoint (see https://github.com/stac-utils/pystac-client/blob/5d7510c5307f04cdbd3bd694f4b919a9bbf9c275/pystac_client/client.py#L182-L1850).

It doesn't look like https://cmr.earthdata.nasa.gov/stac/OB_DAAC currently includes the collections conformance class at https://api.stacspec.org/v1.0.0-rc.1/collections/, despite it (I think) being implemented. Would it be possible to add that conformance class?

[william-valencia]

https://bugs.earthdata.nasa.gov/browse/CMR-10209 created to track this request.