refactor language filtering to a single function

project/dalia/curation/suggest/disciplines.py

project/dalia/curation/suggest/languages.py

project/dalia/curation/suggest/learning_resource_types.py

project/dalia/curation/suggest/media_types.py

project/dalia/curation/suggest/proficiency_levels.py

project/dalia/curation/suggest/relation_types.py

project/dalia/curation/suggest/target_groups.py

project/dalia/query/communities/one_to_one_metadata.py

project/dalia/query/items/metadata/disciplines.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/proficiency_levels.py

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

project/dalia/query/utils.py

tests/project/dalia/query/labels/test_label_service.py