feat(rdf): support serialization of DatasetSeries from RDF and link c…

[hcvdwerf]

@amercader I created this pull request to make serialisation of dataseries possible into ckan model

What I have done:

1. Enabling DatasetSeries Serialization

You extended CKAN's DCAT RDF support to correctly serialize and parse datasets of type dcat:DatasetSeries based on DCAT-AP 3.0:

• Identified where DatasetSeries type detection happens via RDF type triple (rdf:type dcat:DatasetSeries).

• Implemented logic in EuropeanDCATAP3Profile.parse_dataset to:

  • Set "type": "dataset_series" if triple is present.
  • Populate series_order_field and series_order_type with default fields

2. Handling in_series Field Extraction and Linking

I added logic to ensure dataset membership in a series is handled cleanly:

• Centralized the logic to extract dcat:inSeries references in the main datasets() function (outside parse_dataset()).
• Used a series_mapping (via guid) to resolve URIs to internal CKAN id values.

3. Scheming dataseries

I added a prorperty into the scheming dataseries YAML for:

• series_order_field , series_order_type and dataset_series_in_series

• Clarified that these require:

  convert: convert_to_extras

check ckan/ckanext-dataset-series#9
to persist properly as extras.