feat: Add Billings & Payments and Testimonials settings pages for agent and user roles, and refactor notification settings form.

src/components/settings/index.ts

@@ -5,3 +5,4 @@ export { PasswordSecurityForm } from './PasswordSecurityForm';
 export { NotificationsForm } from './NotificationsForm';
 export { PrivacyForm } from './PrivacyForm';
 export { TwoFactorSettings } from './TwoFactorSettings';
+export { SubscriptionForm } from './SubscriptionForm';