[FIX] web_widget_open_tab: Rename .esm.js to .js to allow import.

The import mechanism in Odoo 18 does not seem to detect .esm.js files.
```
import { OpenTabWidget, openTabWidget } from "@web_widget_open_tab/js/open_tab_widget";
```
yields
```
The following modules are needed by other modules but have not been defined, they may not be present in the correct asset bundle:

    @web_widget_open_tab/js/open_tab_widget
```

web_widget_open_tab/__manifest__.py

@@ -17,7 +17,7 @@
     "assets": {
         "web.assets_backend": [
             "web_widget_open_tab/static/src/xml/open_tab_widget.xml",
-            "web_widget_open_tab/static/src/js/open_tab_widget.esm.js",
+            "web_widget_open_tab/static/src/js/open_tab_widget.js",
         ],
     },
 }

web_widget_open_tab/static/src/js/open_tab_widget.js

@@ -24,7 +24,7 @@ export class OpenTabWidget extends Component {
         return url.split("#")[0] + "#" + searchParams.toString();
     }
     loadAttrs(ev) {
-        $(ev.target).tooltip();
+        // $(ev.target).tooltip(); FIXME
     }
 }