Update sitemap pipeline, slow down harvester, fix failure with no transforms, per default json-ld only

through the CLI. Restructured the pipeline code.
Introduce a first version of a Harvester class that one might have a
common interface for different pipelines and harvesters.
Delete the gitlab_project_jsons which do not belong here.
Also allow now to provide a base save path for the whole pipeline.

Reorder folder structure for openaire mining examples and add table generator files, mapping for rare, re3data and licenses

to map xml files to json with prior adjustments.
mapping util contains some functions to apply jq mappings