Block all worker version writes through API

Refs https://redmine.teklia.com/issues/2820

We need to start the transition away from worker version, to rely only on worker runs.

During release 1.4.0 we'll prevent any API user to write a worker version. The field is kept, but should raise an 400 HTTP error as soon as it's set to something. The idea behind this is to actually block workers & other users, instead of silently ignoring them and creating tons of manual ML results.

Affected endpoints are:

• CreateClassification
• CreateClassifications
• CreateElement
• CreateElements
• CreateElementTranscriptions
• CreateEntity
• CreateMetaData
• CreateMetaDataBulk
• CreateTranscription
• CreateTranscriptionEntity
• CreateTranscriptions
• RejectClassification
• ValidateClassification