/processes endpoint improvements

[clausmichele]

Currently the /processes endpoint exposes the content of two json files containing the set of processes implemented in Python and WCPS. We should expose only the ones for Python if no WCPS Collection is exposed. See here:

openeo-spring-driver/src/main/java/org/openeo/spring/api/ProcessesApiController.java

Line 131 in 657d268

final Map<Resource, EngineTypes> res2eng = new LinkedHashMap<>();

Additionally, instead of a file based, we can use the /processes endpoint I added to the openeo_odc_driver here: https://github.com/Open-EO/openeo_odc_driver/blob/6a6b3a9dd43496477a0e915e0911f9757782582b/openeo_odc_driver/odc_backend.py#L177

[pierocampa]

ciao @clausmichele ,
Ok, now the list of processes for a backend is shown only if the related endpoint is actually configured (that means if org.openeo.[engine].endpoint is set) (see 88311b3)

This change has been pushed to master, but the feature/stac_1.1.0 has been rebased again so to be up-to-date.

I also specified the new processes list to be fetched from the /processes endpoint of the ODC backend in the development Spring server, so no file is needed anymore.