Migrate demo server setup to GitOps

[justb4]

The current setup to maintain and deploy the various services is semi-automated: Ansible is used, but with full GitOps, coupling GitHub, GH Workflows with Ansible, we get several advantages:

• as pygeoapi Docker builds are moved to GH Workflows, will be easier to integrate (now HTTP-callback from DockerHub)
• any other service like the "Home" page will be automagically deployed on GH push
• repo is well-prepared to later move to OSGeo SAC infrastructure

As example of a fully fledged GitOps pygeoapi deployment the Geonovum OGC API Testbed project can serve as example:

• https://apitestdocs.geonovum.nl/
• https://github.com/Geonovum/ogc-api-testbed

[justb4]

Duplicate of #27, closing.