Improve support for the Federation Extension

[m-mohr]

In the EOEPCA+ project, we made an evaluation of the federation-related functionality available through the openEO Julia 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 R:

• 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

The following issues have been identified for the programatic access through the UI interfaces such as Jupyter and RMarkdown:

• 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)