Feature: Add better skos support: Schemes, Collections, Skos XL, SKOS mappings and Concepts tree filtering

[syphax-bouazzouni]

Context

The PR extract the changes done in AgroPortal to support better SKOS resources, in 2022. All the details are described here
agroportal/project-management#262

Changes

• Update Instance model to use Goo not a raw SPARQL query (41a2525)
• Extract the classes tree and sorting to external modules (89d7675)
• Add the skos new models for collection, schemes and skosxl with tests (7fce23e)
• Add for classes the properties to know on which scheme and collection they belong (3d03c1f)
• Update the logic of submission roots to filter by schemes or collections (bcea238)
• Add for the ontology endpoint links to its related schemes, collections and skos xl labels (0184224)
• Add tests to check the submission roots filtering by scheme or collection (c39d833)
• Add internal skos mappings extraction (6bb3412)