When an include is not surrounded by empty lines, its content is inlined
on the same line as the adjacent content. That can lead to broken tags
and other display issues.
This PR fixes all such includes and introduces a validation step that
forbids introducing the same problem again.
There was already a check for section duplication, but only in "How to
fix it". This changes the test to cover all sections.
And fixing the rules that this new validation fails on.
Also making test_modify_rule.py run on Windows.
---------
Co-authored-by: Christophe Zürn <36889251+christophe-zurn-sonarsource@users.noreply.github.com>
