restore non book bundle solution to wxt-6.1.x

Problem/Motivation

The book module was removed from core in Drupal 11.0.x

WxT 6.1.x has Drupal 11.1.8 currently. During the upgrade the core patch we were using for non-book bundles to have books was broken and it was removed.

Since then, the solution was merged into the contrib version of book where the core module was moved to.

Rapid development has been underway in the book module ever since it was removed from core. The speed of progress is fast now that it's no longer in core. Our fix was merged into the 3.0.x version of book however we cannot yet use 3.0.x, we must use 2.0.x , therefore I am preparing a backport of the fix for 2.0.x

Steps to reproduce

See problem statement

Proposed resolution

A specific 2.0.x version of book and a specific patch.

Remaining tasks

Develop, review and test.

User interface changes

As discussed in the problem statement.

API changes

Some changes to the book module and it affects the book.settings.yml

Data model changes

book.settings.yml changes.