[profile] Various HTML fixes:

- Wrap block level elements within block level elements, not inline.
- Avoid empty blocks.
- Change `<hr>` in lists into allowed type of children.
- Fix duplicated ID (some change that was not propagated across the template?).
- Make the anchor optional in the navbar (interactive elements (`a`, `input`, `button`…) should not appear into other interactive elements).
- Remove redundant `role` on main navigation.
- Make the modal a modal with `role="dialog".
- Use `button` instead of form-less `label`.

bookwyrm/templates/snippets/shelf_selector.html

@@ -18,7 +18,7 @@
 </li>
 {% endif %}
 {% endfor %}
-<hr class="navbar-divider">
+<li class="navbar-divider" role="presentation"></li>
 <li>
     <form class="dropdown-item pt-0 pb-0" name="shelve" action="/unshelve/" method="post">
         {% csrf_token %}