Add test data instances for testing purporses.

tests/data/instances/article_eomar_datacite.jsonld

tests/data/instances/codemeta.jsonld

tests/data/instances/collection_fzj_datacite.jsonld

tests/data/instances/creativework_fzj_datacite.jsonld

tests/data/instances/dataset_fzjdatacite.jsonld

tests/data/instances/dataset_juelichdata.ttl

tests/data/instances/dataset_pangaea.jsonld

tests/data/instances/dataset_rodare.jsonld

tests/data/instances/software_rodare.jsonld