integration_url_modal: Fix multiple modals opening.

Earlier the `generate integration url` button (fa-link) was still in
focus even after opening the modal.
This caused the modal to open multiple times when the user pressed the
enter key. This commit fixes that issue by focusing on the input
dropdown when the modal is opened.

web/src/integration_url_modal.ts

@@ -278,5 +278,8 @@ export function show_generate_integration_url_modal(api_key: string): void {
             return;
         },
         post_render: generate_integration_url_post_render,
+        on_shown() {
+            $("#integration-name_widget").trigger("focus");
+        },
     });
 }