Vanilla remembers the page number of lecterns and uses it for the GUI right-click. We should:

1. Use this for saving data instead of saving data ourselves separately. This would mean we no longer need any form of WorldStorage, since vanilla handles all the storing we need.
2. When immersively page-turning, set the GUI's page number, and vice-versa.

Versions ported to:

• 1.21.1
• 1.20.4
• 1.20.2
• 1.20.1
• 1.19.4
• 1.19.3
• 1.19.2
• 1.18.2