Added possibility for directives to have 'extra-options' defined in c…

[MaximilianSoerenPollak]

This is the fourth 'split' PR that was discussed for splitting the big one into smaller ones. This one here #80

Note: PR depends on another. #83.

This PR adds the capability of the directives declared in the package to contain extra_options defined via the sphinx-needs option in conf.py.

Note: This PR has a similar issue as #83 issue being that the 8.1.3 Sphinx tests fail, with the same error message.

FAILED tests/test_custom_template.py::test_custom_koi8_template[test_app0] - sphinx.errors.ThemeError: An error happened in rendering the page index.
FAILED tests/test_custom_template.py::test_custom_utf8_template[test_app0] - sphinx.errors.ThemeError: An error happened in rendering the page index.
FAILED tests/test_custom_template.py::test_custom_template[test_app0] - sphinx.errors.ThemeError: An error happened in rendering the page index.

More exact:

E           sphinx.errors.ThemeError: An error happened in rendering the page index.
E           Reason: TemplateNotFound("'about.html' not found in ['/tmp/tmptxv71yyp/custom_tr_template/_templates', '/home/maxi/tmp/testing/sphinx-test-reports/.nox/tests-3-12-sphinx-8-1-3/lib/python3.12/site-packages/sphinx/themes/basic']")

.nox/tests-3-12-sphinx-8-1-3/lib/python3.12/site-packages/sphinx/builders/html/__init__.py:1201: ThemeError