FIXES: https://github.com/executablebooks/jupyter-book/issues/1049

The `_filename_to_title()` function runs `path.with_suffix("")`.

The suffix is currently stripped in  `_content_path_to_yaml()` and then again in `_filename_to_tile()`. If the filename contains a `.` the second call splits the filename at the point.

Correction is: don't strip suffix in   `_content_path_to_yaml(()` .

Co-authored-by: Chris Holdgraf <choldgraf@berkeley.edu>

Ensure sorting of files in directory

This PR brings improvements to `PDF` builds via `LaTeX` by incorporating the
[jupyterbook-latex](https://github.com/executablebooks/jupyterbook-latex

) extension.

This initial release:

1. harmonises the document structure for `html` and `latex` outputs, by implementing support for `part`/`chapter` structures in the `_toc.yml` for PDF via LaTeX,
2. brings support for the jupyter-book directive `tableofcontents` to PDF via LaTeX, and
3. adds support for commonly used tags on `code-cell` directives (such as `hide-cell`) to PDF via LaTeX

Co-authored-by: mmcky <mamckay@gmail.com>
Co-authored-by: mmcky <mmcky@users.noreply.github.com>

* update version and CHANGELOG

* update CHANGELOG

* add in other commits to CHANGELOG

* fix link and PR ref

* suppressing resolve_any_xref issue

* modified fixture files

referencess.bib -> references.bib

minor typo: your --> you

The example was not the same as the code, which is confusing especially for the `:align: center` option!

* RELEASE: v0.9.0