Dutch API Design Rules pygeoapi instance

[GeoSander]

In order to deploy a new pygeoapi instance that is configured to adhere to the Dutch API Design Rules (ADR), we ideally use the same Docker image, but with another configuration YAML (with api_rules section).
At the same time, we wish to keep the old/current pygeoapi up-and-running.
Therefore, we add a second Docker service to the docker.compose.yml of pygeoapi, that will use another configuration and root context path.

So the old/current pygeoapi instance will stay at https://apitestbed.geonovum.nl/pygeoapi.
The new pygeoapi instance that adheres to the Dutch ADR will run at https://apitestbed.geonovum.nl/adr_pygeoapi.

[GeoSander]

Completed by making some final changes to geopython/pygeoapi#1152 and merging them into https://github.com/geopython/pygeoapi/tree/crs-features-ogc-adr, which the pygeoapi testbed uses for the Docker source image.