bulma (call): add a button for screen sharing: - add a button for screen sharing, only on desktop - split `muted` state to `inactive` and `muted` where `muted` is only about the color - use the `inactive` state with an other color (in `screen-off` class) to indicate when screen is not shared rel 432

{% if status == none %}
    <div class="call_status notification is-info column my-0">
    </div>
{% elif status == "dialing" %}
    <div class="call_status notification is-info column my-0">
        <p>{% trans %}Calling {{name}}…{% endtrans %}</p>
    </div>
{% endif %}