[IMP] web: enable extension of 'X2ManyFieldDialog'

This commit simply exports the 'X2ManyFieldDialog' component from its
definition file.

That way it can be properly extended / patched when necessary.

Task-2981969

X-original-commit: 881d8ef998b8a98b89ccbab93dcf1ed76ca1193b
Part-of: odoo/odoo#100940

addons/web/static/src/views/fields/relational_utils.js

@@ -400,7 +400,7 @@ export function useOpenMany2XRecord({
 // X2Many
 //
 
-class X2ManyFieldDialog extends Component {
+export class X2ManyFieldDialog extends Component {
     setup() {
         this.archInfo = this.props.archInfo;
         this.record = this.props.record;