move information on label retrieval to FacetObject

project/dalia/query/items/facets/facet_objects.py

project/dalia/query/items/metadata/languages.py

...ect/dalia/query/items/metadata/learning_resource_types.py

project/dalia/query/items/metadata/media_types.py

project/dalia/query/items/metadata/target_groups.py

project/dalia/query/labels/label_service.py

...y/items/basic_search_filters/test_basic_search_filters.py

tests/project/dalia/query/items/facets/utils.py