bulma (file, components): fix color fo icons: icons have no color specified anymore for a while, and use the color of parent elements. As they are often used in a `<a>` element (to work without javascript), they are often using a link color. This commit change a few icons to use a dark color instead.

{% macro form(action='', class='') %}
<form method="post" action="{{action}}" {{ {'class': class}|xmlattr }} {{kwargs|xmlattr}} >
    {% if csrf_token is defined %}
        <input type="hidden" name="csrf_token" value="{{csrf_token}}">
    {% endif %}
    {{ caller() }}
</form>
{% endmacro %}