Implement release check events and abort action

[jens-kuerten]

ReleaseCheck Events:

Adds new ReleaseCheck Events, which are triggered before an object is released and allow the release to be aborted with an Action.

• DocumentReleaseCheck
• PartReleaseCheck
• EngineeringChangeCheck

AbortAndShowErrorAction:

Adds AbortAndShowErrorAction (already existed in csfunctions, but wasn't usable)
Actions can be returned directly from Functions. (csfunctions will automatically wrap them in a WorkloadResponse)

Example:

def prevent_doc_release(metadata, event: DocumentReleaseCheckEvent, service):
    # prevent release if a document doesn't contain any files
    for doc in event.data.documents:
        if not doc.files:        
            return AbortAndShowErrorAction(
                message=f"Can't release because document {doc.z_nummer} doesn't contain a file."
            )

Misc:

• Removed the custom constructors on events, because they were causing typing issues and are not required.