ENH: Enable support for format in _toc.yml

[mmcky]

Description / Summary

We should explicitly link the format types that are defined in _toc.yml to the operation of this extension and ensure support for jb-article and jb-book.

Documentation for the latest format definitions are available here:

https://jupyterbook.org/customize/toc.html#

and definitions are here:

https://sphinx-external-toc.readthedocs.io/en/latest/user_guide/sphinx.html#using-different-key-mappings

We have tested against jb-book primarily so we should do additional testing for jb-article

Value / benefit

This will tie in nicely with the available metadata now available through the format key in _toc.yml to enable more targeted assumptions in the LaTeX translation. If we know the jb-article key is provided we can make more assumptions about the document structure when parsing the sphinx.ast.

Implementation details

TBD

Tasks to complete

• review the best way to add jb-article and jb-book

[mmcky]

@AakashGfude this is the issue I put together to start thinking about how we can tailor this extension to use the metadata contained in _toc.yml to make tighter and more accurate assumptions etc.