Enable datetime / sortby / properties queries for Postgres provider

[KoalaGeo]

Is your feature request related to a problem? Please describe. We have a lot of data in Postgres, it'd be great to connect this to pygeoapi with the full query functionality the same as an elastic search or mongodb provides

Describe the solution you'd like When using Postgres as a provider for OA-Features be able to query datetime, sortby and properties

Describe alternatives you've considered None

Additional context None

[ksonda]

@webb-ben @dblodgett-usgs we are probably going to need to do this for the global river runner anyway.

[webb-ben]

I've added to the select_properties, skip_geometry, and sortby to the postgres provider when tinkering around for river runner. I don't know if this is still relevant @ksonda but figured I would loop back to this.