Add missing endpoint helpers
As https://gitlab.com/teklia/workers/base-worker/-/issues/86 points out, every endpoint does not have a helper. It would be nice to have that are most used, here is a list of relevant ones:
- ListElementMetaData (https://gitlab.com/teklia/workers/base-worker/-/issues/86)
- ListCorpusEntities
- ListTranscriptionEntities
- CreateElementTranscriptions
- CreateMetaDataBulk