- Added testing to cover warning cases.
- Refactored logic to be simpler and move much of the business out of
the controller.
- Added new message that's more suitable to the case this was handling.
- For detecting an outdated draft, checked the draft created_at time
instead of updated_at to better fit the scenario being checked.
- Updated some method types to align with those potentially being used
in the logic of the code.
- Added a cache of shown messages on the front-end to prevent them
re-showing on every save during the session, even if dismissed.
- Fixed page editor default focus not working as expected due to
misnamed attribute.
- Added owned_by to relevant areas of the API including the docs.
- Made book relation on page accessible even if deleted since it could cause an issue on views, such as audit trail, when the relation is accessed when the book is deleted.
