Move openBanWindow to its own separate file

It is now shared between the admin view and the inline view.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/templates/board/base.html

@@ -12,6 +12,7 @@
         <script src="{% static 'board/winbox.bundle.js' %}"></script>
         <script src="{% static 'board/post.js' %}"></script>
         {% if perms.board.create_ban %}
+            <script src="{% static 'board/ban_window.js' %}"></script>
             <script src="{% static 'board/ban_menu.js' %}"></script>
         {% endif %}
         {% block extrajs %}{% endblock %}