This ticket is about creating a mediainfo entity on demand when adding a statement for the first time. A related task is T134259 which is about creating a mediainfo entity on demand when hitting save the first time after adding labels, descriptions and/or aliases.
Discussed with @daniel. Possible task breakdown:
* Refactor EntitySavingHelper:
* [ ] Simple refactoring (without introducing new functionality) of EntityLoading and SavingHelper to `EntitySavingHelper extends EntityLoadingHelper`. Or use composition so that the SavingHelper gets a LoadingHelper.
* [ ] Add new features to Loading and SavingHelper to support auto-creation of entities.
* Support editing non-existing MediaInfo entities via `SetClaim` API module
* [ ] Support auto-creation and the `new` parameter in all API modules that are //not// based on `ModifyEntity`.
* [ ] Possibly discuss if the `new` parameter really should be supported by all API modules.