Implement support for the Federation Extension

[m-mohr]

In the EOEPCA+ project, we made an evaluation of the federation-related functionality available through the openEO Python Client.
The Federation Extension can be found here: https://github.com/Open-EO/openeo-api/blob/draft/extensions/federation/README.md

The following issues have been identified for the programatic access in Python:

• GET / - Show federation backends (federation) -> possible but undocumented RESTCapabilities undocumented #610
• federation:missing can't be accessed through the corresponding functions for the following endpoints:
  • GET /collections
  • GET /processes
  • GET /process_graphs
  • GET /files
  • GET /jobs
  • GET /jobs/:id/logs
  • GET /services
  • GET /services/:id/logs
• federation:backends can't be accessed through the corresponding functions for the following endpoints:
  • POST /validation

The following issues have been identified for the programatic access through the UI interface in notebooks such as Jupyter:

• federation:missing can't be accessed through the corresponding functions for the following endpoints:
  • GET /collections
  • GET /processes
  • GET /file_formats
  • GET /process_graphs
  • GET /files
  • GET /jobs
  • GET /jobs/:id/logs (missing upstream in Vue Components)
  • GET /services
  • GET /services/:id/logs (missing upstream in Vue Components)
• federation:backends can't be accessed through the corresponding functions for the following endpoints:
  • POST /validation
  • GET /udf_runtimes per version (missing upstream in Vue Components)
  • GET /services/{id} (missing upstream in Vue Components)

Related issue for the upstream issues in Vue Components: Open-EO/openeo-vue-components#97