Resolve "OER: Man verliert die Suchergebnisse, wenn man Material anschaut"

Closes #2831

Merge request studip/studip!1917

app/views/oer/market/_material_short.php

@@ -5,7 +5,7 @@
  */
 ?>
 <article class="contentbox">
-    <a href="<?= $controller->link_for('oer/market/details', $material) ?>">
+    <a href="<?= $controller->link_for('oer/market/details', $material) ?>" target="_blank">
         <header>
             <h1>
                 <?= $material->getIcon()->asImg(['class' => 'text-bottom']) ?>

app/views/oer/market/_searchform.php

@@ -162,7 +162,7 @@
 <ul class="results oer_material_overview" v-if="results && results.length > 0">
     <li v-for="result in results" :key="result.material_id">
         <article class="contentbox" :title="result.name">
-            <a :href="getMaterialURL(result.material_id)">
+            <a :href="getMaterialURL(result.material_id)" target="_blank">
                 <header>
                     <h1>
                         <studip-icon :shape="getIconShape(result)"