Allow books to use an index-based category view instead of quest-based

[klikli-dev]

• Can we support this per-category?
• Or just per-book?

Use search screen logic/layout for index rendering

• [x] Route all state changes (open/close book, category, entry) through gui manager?
• [x] Book Overview Screen variant that is index-based
  • [x] search button
  • [x] Optional description for the first page of the book index screen
  • [x] read all button
• [x] Book Category Screen that is index-based
  • [x] Optional description for the first page of a category's index
• [x] For books with a node overview screen but index categories, create a dummy node category screen to render as a background
  • [x] Important: Figure out a way to enable category navigation. E.g. in fabric we currently do not have multi gui layers
• [x] add proper gui layers to fabric?
• [x] Check TODO comments in code
• [x] reduce datagen obligations for index-only books
  • [x] don't need entry parents (probably not mandatory anyway currently)
  • [x] auto-set category mode to index? -> the book is doing this automatically now independent of the data
• [x] allow to specify entry order
  • [x] add internal counter to datagen for default order?
• [x] refactor gui package to be organized by node vs index instead of parent/category?
• [x] Test JEI gui integration and restoring -> no JEI yet
• [x] Check and test search screen & screen state/stack handling
• [x] update docs