feat: create deferred mode in CrudStore, undo/redo store
Includes a lot of documentation in the CrudStore as well, both for using it and modifying it. (The file is almost 50% comments!
Undo/Redo (and keeping track of changes to commit) has not yet been integrated into the Deferred CrudStore, as it requires structural changes that are too large to fit in a single MR.