Improve searchbox accessibility (#760)

* Set field key for search result options label

* Add playwright test

* Add role attr to search dialog

src/components/searchbox/NodeSearchBox.vue

@@ -40,6 +40,7 @@
       auto-option-focus
       force-selection
       multiple
+      :optionLabel="'display_name'"
     >
       <template v-slot:option="{ option }">
         <div class="option-container">