update distributedsearch configuration

[tomkralidis]

Overview

This PR updates federated search configuration to allow for merging of federated results (on .../item?distributedSearch=true as part of the mean features array (vs. the federatedSearchResults array [default]) by:

• renaming federatedcatalogues (array) in to distributedsearch (object) with a merge_results (boolean, default false ) directive.

Related Issue / Discussion

None

Additional Information

None

Contributions and Licensing

(as per https://github.com/geopython/pycsw/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pycsw. I confirm that my contributions to pycsw will be compatible with the pycsw license guidelines at the time of contribution.
• I have already previously agreed to the pycsw Contributions and Licensing Guidelines

[tomkralidis]

Note:

• validation CI failures are unrelated
• build CI failure should be fixed once geopython/pycsw:latest is built/updated with Fix refs #1223

[tomkralidis]

CI failures fixed in e95a32b and 4adca14