Change implementation of frontmatter generator (__generate_frontmatter() in EditionParser) to handle all types of frontmatters

[kodzonko]

Current implementation only handles /matter/foreword.html, /matter/introduction.html and /matter/acknowledgements.html frontmatter types. For other files it throws ValueError. We need to make it cover all types of frontmatters or be less strict about unknown types (i.e. not raise an error) otherwise we cannot execute the app.

A piese of code which needs to be reworked (sutta_publisher/src/sutta_publisher/edition_parsers/base.py):

for suffix in matter_paths:
    response = requests.get(url.format(matter=suffix, working_dir=working_dir))
    response.raise_for_status()

    match suffix:
        case "/matter/foreword.html":
            matters_dict["foreword"] = response.text

        case "/matter/introduction.html":
            matters_dict["introduction"] = response.text

        case "/matter/acknowledgements.html":
            matters_dict["acknowledgements"] = response.text

        case _:
            raise ValueError("Not supported frontmatter type")

return matters_dict

[kodzonko]

This will be implemented along with issue #61 on branch 61-Implement-fetching-additional-headers-and-reorganizing-headings-numbers-in-a-base-html.