Clear input after option selection in tomselect fields

Fixes issue #1264

assets/controllers/elements/select_multiple_controller.js

@@ -35,6 +35,8 @@ export default class extends Controller {
             maxItems: 1000,
             allowEmptyOption: true,
             dropdownParent: dropdownParent,
+            selectOnTab: true,
+            clearAfterSelect: true,
             plugins: ['remove_button'],
         });
     }