Split the API functions into multiple files

src/api.js

src/api/classification.js

src/api/corpus.js

src/api/element.js

src/api/elementType.js

src/api/entity.js

src/api/export.js

src/api/files.js

src/api/image.js

src/api/index.ts

src/api/ingest.js

src/api/job.js

src/api/memberships.js

src/api/metadata.js

src/api/mlclass.js

src/api/model.js

src/api/oauth.js

src/api/ponos.js

src/api/process.js

src/api/repository.js