Add Practical Examples for PayPal Subscriptions Connector

[RNViththagan]

Purpose

This PR adds two practical examples to the ballerinax/paypal.subscriptions connector to demonstrate real-world use cases for managing subscription-based billing.

Examples

1. Create and List Plans: Creates a subscription plan and lists all available plans.
2. Monitor and Manage Subscription Status: Retrieves a subscription's status and suspends or reactivates it based on its state.

Checklist

• Updated the changelog
• Added tests
• Checked native-image compatibility

[ThisaruGuruge]

Good job!