Chiseled bookshelves do not support structure mirroring transformations

Despite chiseled bookshelves rotating and mirroring their facing direction correctly, their slots are not mirrored when it would make sense to do so. As a result, chiseled bookshelves break the symmetry of a mirrored structure.

Reproduce the Issue:

Save a chiseled bookshelf with top left slot filled as a structure via a structure block, load the structure with mirroring, notice that it's still the top left slot, and not top right that's filled: