add render_dropdown_item ?

[landryb]

not finding a way to properly render dropdown menu items, I've had the need to complement render_nav_item by render_dropdown_item to add items to bootstrap dropdown menus.

the quickly hardcoded version is below, i can adapt it to provide the use_li conditional

{% macro render_dropdown_item(endpoint, text, _badge='', _badge_classes='badge text-bg-light') %}
    {% set active = True if request.endpoint and request.endpoint == endpoint else False %}
    <li>
    <a class="dropdown-item{% if active %} active" aria-current="page{% endif %}"
       href="{{ url_for(endpoint, **kwargs) }}">
        {{ text }} {% if _badge %}<span class="{{ _badge_classes }}">{{ _badge }}</span>{% endif %}
    </a>
    </li>
{% endmacro %}

would that be interesting as a PR ?