refactor(header/notice): convert JS to stimulus

app/javascript/controllers/dsfr_header_controller.ts

@@ -0,0 +1,13 @@
+import { ApplicationController } from './application_controller';
+
+export class DSFRHeaderController extends ApplicationController {
+  static targets = ['notice'];
+
+  declare readonly noticeTarget: HTMLElement;
+
+  closeNotice() {
+    this.noticeTarget.parentNode?.removeChild(this.noticeTarget);
+
+    this.element.classList.remove('fr-header__with-notice-info');
+  }
+}