ZODB Components: Revert "Also, allow developer to call validate action from 'modified' state to handle import use case" (part of 1cb2dc4c).

This was badly implemented as it didn't handle the following use cases:
  * {draft,invalidated} => validated.
  * clearRecordedPropertyDict() was not called on re-validate.

For now, re-validate through modifying {text_content,reference,version}.