feat(ios): create paywall api (#13602)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- New Features
- Introduced a new iOS Paywall plugin with a simple API to display a
paywall and receive a success response.
  - Added JavaScript wrapper and type definitions for easy integration.

- Refactor
  - Reorganized the iOS project structure for plugins.

- Chores
- Removed unused legacy iOS plugins to streamline the app and reduce
build complexity.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/ios/src/plugins/paywall/definitions.ts

@@ -0,0 +1,5 @@
+export interface PayWallPlugin {
+  showPayWall(options: {
+    type: string;
+  }): Promise<{ success: boolean; type: string }>;
+}

packages/frontend/apps/ios/src/plugins/paywall/index.ts

@@ -0,0 +1,8 @@
+import { registerPlugin } from '@capacitor/core';
+
+import type { PayWallPlugin } from './definitions';
+
+const PayWall = registerPlugin<PayWallPlugin>('PayWall');
+
+export * from './definitions';
+export { PayWall };