backoffice: fix display of "add related" button in grid widgets (#53192)

wcs/qommon/static/css/dc2/admin.scss

@@ -2126,6 +2126,14 @@ div.timetable-widget {
 	}
 }
 
+.wcs-widget-select2-container {
+	display: flex;
+	.add-related {
+		margin-top: 2px;  // == margin-top of span.select2-container
+		margin-left: 3px;
+	}
+}
+
 .wcs-block-with-remove-button {
 	.BlockSubWidget {
 		position: relative;

wcs/qommon/templates/qommon/forms/widgets/select_jsonp.html

@@ -1,6 +1,7 @@
 {% extends "qommon/forms/widget.html" %}
 {% load i18n %}
 {% block widget-control %}
+<div class="wcs-widget-select2-container">
 <select id="form_{{widget.name}}" name="{{widget.name}}"
     data-select2-url="{{widget.get_select2_url}}"
     {% if widget.value %}data-value="{{ widget.value }}"{% endif %}
@@ -12,4 +13,5 @@
     href="{{ widget.add_related_url }}?_popup=1"
     title="{% blocktrans with card=widget.get_title %}Add another {{ card }}{% endblocktrans %}">+</a>
 {% endif %}
+</div>
 {% endblock %}