Bug 38201: Add optional :multiple attribute to 'select' form elements

Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

koha-tmpl/intranet-tmpl/prog/js/vue/components/FormElement.vue

@@ -96,6 +96,7 @@
             :options="selectOptions"
             :required="!resource[attr.name] && attr.required"
             :disabled="disabled"
+            :multiple="attr.allowMultipleChoices"
             @option:selected="attr.onSelected && attr.onSelected(resource)"
         >
             <template v-if="attr.required" #search="{ attributes, events }">