Include C construct directives for RST checks

[hugovk]

Fixes #108.

Add the "cross-referencing C constructs" from:

https://www.sphinx-doc.org/en/master/usage/domains/c.html#cross-referencing-c-constructs

The 3.13/Ubuntu job fails as expected, because it also checks the friend projects, and finds the two CPython examples mentioned in the issue:

sphinx-lint/tests/fixtures/friends/cpython/Doc/c-api/function.rst:171: default role used (hint: for inline literals, use double backticks) (default-role)
sphinx-lint/tests/fixtures/friends/cpython/Doc/c-api/code.rst:171: default role used (hint: for inline literals, use double backticks) (default-role)

Also Git ignore coverage data files (for example: .coverage.Hugos-MacBook-Pro.local.95733.XMjioudx).

[AA-Turner]

In https://github.com/sphinx-contrib/sphinx-lint/pull/26/files#diff-91cfb2b6e0fd957947632d6fee27472ac6aaff7d825f02bdea3e54cda9005b0b, which I haven't had the time to revisit, I enumerated the list of directives more exhaustively:

DIRECTIVES_CONTAINING_RST = [
    # reStructuredText directives:
    'admonition', 'attention', 'caution', 'class', 'compound', 'container',
    'danger', 'epigraph', 'error', 'figure', 'footer', 'header', 'highlights',
    'hint', 'image', 'important', 'line-block', 'list-table', 'math', 'meta',
    'note', 'parsed-literal', 'pull-quote', 'replace', 'sidebar', 'tip',
    'topic', 'warning',
    # Added by Sphinx:
    'acks', 'centered', 'codeauthor', 'default-domain', 'deprecated(?!-removed)',
    'describe', 'highlight', 'hlist', 'index', 'literalinclude', 'moduleauthor',
    'object', 'only', 'rst-class', 'sectionauthor', 'seealso', 'tabularcolumns',
    'toctree', 'versionadded', 'versionchanged',
    # Added by Sphinx (since removed):
    'highlightlang',  # removed in Sphinx 4.0
    # Added by Sphinx (Standard domain):
    'cmdoption', 'envvar', 'glossary', 'option', 'productionlist', 'program',
    # Added by Sphinx (Python domain):
    'py:attribute', 'py:class', 'py:classmethod', 'py:currentmodule', 'py:data',
    'py:decorator', 'py:decoratormethod', 'py:exception', 'py:function',
    'py:method', 'py:module', 'py:property', 'py:staticmethod',
    'attribute', 'class', 'classmethod', 'currentmodule', 'data',
    'decorator', 'decoratormethod', 'exception', 'function',
    'method', 'module', 'property', 'staticmethod',
    # Added by Sphinx (C domain):
    'c:alias', 'c:enum', 'c:enumerator', 'c:function', 'c:macro', 'c:member',
    'c:struct', 'c:type', 'c:union', 'c:var',
    'cfunction', 'cmacro', 'cmember', 'ctype', 'cvar',
    # Added by Sphinx (sphinx.ext.todo):
    'todo', 'todolist',
    # Added in Sphinx's own documentation only:
    'confval', 'event',
    # Added in the Python documentation (directives):
    'audit-event', 'audit-event-table', 'availability',
    'deprecated-removed', 'impl-detail', 'miscnews',
    # Added in the Python documentation (objects with implicit directives):
    '2to3fixer', 'opcode', 'pdbcommand',
    # Added in the Python documentation (Python domain):
    'coroutinefunction', 'coroutinemethod', 'abstractmethod',
    'awaitablefunction', 'awaitablemethod',
    'py:coroutinefunction', 'py:coroutinemethod', 'py:abstractmethod',
    'py:awaitablefunction', 'py:awaitablemethod',
]

DIRECTIVES_CONTAINING_ARBITRARY_CONTENT = [
    # reStructuredText directives:
    'code', 'code-block', 'contents', 'csv-table', 'date', 'default-role',
    'include', 'raw', 'restructuredtext-test-directive', 'role', 'rubric',
    'section-numbering', 'sectnum', 'sourcecode', 'table', 'target-notes',
    'title', 'unicode',
    # Added by Sphinx (core):
    'cssclass',
    # Added by Sphinx (Standard domain):
    'productionlist',
    # Added by Sphinx (C domain):
    'c:namespace', 'c:namespace-pop', 'c:namespace-push',
    # Added by Sphinx (sphinx.ext.autodoc):
    'autoattribute', 'autoclass', 'autodata', 'autodecorator', 'autoexception',
    'autofunction', 'automethod', 'automodule', 'autonewtypedata',
    'autonewvarattribute', 'autoproperty',
    # Added by Sphinx (sphinx.ext.doctest):
    'doctest', 'testcleanup', 'testcode', 'testoutput', 'testsetup',
    # Added in the Python documentation:
    'limited-api-list',
]

[hugovk]

What do you suggest? Shall we wait for #26 to be merged instead, or merge this as an incremental improvement?