Removes page/chpater addSelect global query, to load book slug, and
instead extracts base queries to be managed in new static class, while
updating specific entitiy relation loading to use our more efficient
MixedEntityListLoader where appropriate.
Related to #4823
- Loaded book_slug as part of chapter/page queries instead of books
being loaded in afterwards.
- Removed unused page method.
- Updated some page queries to load specific attributes.
- 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.
Tools seems to fit better since the classes were a bit of a mixed bunch
and did not always manage.
Also simplified the structure of the SlugGenerator class.
Also focused EntityContext on shelves and simplified to use session
helper.
