Support new version of OGC API based on OpenAPI

OGC web site: https://ogcapi.ogc.org/

The goal of this page is to prepare the Camptocamp-OGC CodeSprint: https://developer.ogc.org/sprints/20/

== The API that concerns GeoMapFish

=== Common https://ogcapi.ogc.org/common/ Are we impacted?

=== Tiles https://ogcapi.ogc.org/tiles/ (accepted) We should update TileCloud-chain probably with https://pypi.org/project/pyramid-openapi3/ and https://pypi.org/project/python-openapi/ Using it didn't look to give any benefit at medium therm

=== Features https://ogcapi.ogc.org/features/ (accepted) No benefit since we didn’t get JSON geometries with CRS and layer. See e.g. https://github.com/opengeospatial/ogc-feat-geo-json https://www.ogc.org/news/ogc-members-propose-new-features-and-geometries-json-standards-working-group-public-comment-sought/ But looks to be abandoned…

=== Styles https://ogcapi.ogc.org/styles/ Are we impacted by legend?

=== Maps https://ogcapi.ogc.org/maps/ Using it didn't look to give any benefit at medium therm

=== Landing page It should work to have the benefit of that.

Landing page implementation impact and action: See how it works with MapServer and QgisServer do we have a page that presents all the projects?

Should we have a URL like `.../mapserv_proxy/<ogs_server_base>/?

I yes we probably should add a new kind of object in GeoMapFish admin.

== Code sprint action

• Tiles: implement it in TileCloud-chain
• Investigate how the Landing page works with MapServer and QGISServer
• Create a table named ‘Base OGC Server’ (if needed)
  • Move into it the field Base URL (sub URL will be in OGC Server), Server Type, Auth type (what about support WFS)
  • The new API will be /mapserv_proxy///…
  • The old API will continue to work (/mapserv_proxy?ogcserver=...)
  • The QGIS server plugin should be updated to support the new schema (URL and database)
• Create an index page on /mapserv_proxy (no sub path and no ogcserver in query string) with a link to the landing pages of all the OGC servers.