use default form CSS in sidebar, replace icon for settings menu, re #3421

Merge request studip/studip!2428

resources/assets/stylesheets/scss/admin-courses.scss

@@ -32,3 +32,14 @@
 #admin-filter-widget .label-text {
     display: block;
 }
+
+.action-menu.filter {
+    margin-left: 1em;
+}
+
+.action-menu.filter:not(.is-open) .action-menu-icon {
+    @include background-icon(settings, clickable, 20);
+    span {
+        display: none;
+    }
+}

resources/vue/components/AdminCourses.vue

@@ -34,7 +34,7 @@
                 </th>
                 <th class="actions">
                     {{ $gettext('Aktion') }}
-                    <studip-action-menu :title="$gettext('Darstellungsfilter')" :items="availableFields" @toggleActiveField="toggleActiveField"></studip-action-menu>
+                    <studip-action-menu class="filter" :title="$gettext('Darstellungsfilter')" :items="availableFields" @toggleActiveField="toggleActiveField"></studip-action-menu>
                 </th>
             </tr>
             <tr v-if="buttons.top">

templates/sidebar/list-widget.php

-<form method="post">
+<form class="default" method="post">
     <?= CSRFProtection::tokenTag() ?>
     <ul class="<?= implode(' ', $css_classes) ?>" aria-label="<?= htmlReady($title) ?>">
     <? foreach ($elements as $index => $element): ?>