Integrating upgraded version

Created by: oblivisheee

This pull request includes significant changes to the project, primarily focusing on the removal of RabbitMQ and the addition of NATS for messaging, as well as updates to configuration files and the addition of new utility functions and tests. Below are the most important changes:

Messaging System Update:

• Removed RabbitMQ configuration and dependencies from docker-compose.yaml, subscription/src/config.rs, and subscription/Cargo.toml. [1] [2] [3]
• Added NATS configuration, dependencies, and a new NatsClient implementation with tests in tests/src/main.rs. [1] [2]

Configuration Updates:

• Updated conf/users-docker-config.json to include NATS bind addresses.
• Added a new tests workspace member in Cargo.toml.

Documentation:

• Updated README.md to include a new /healthy endpoint.

Utility Functions:

• Added new utility functions for handling SurrealDB queries in subscription/src/utils.rs.

Subscription Management:

• Added SQL functions for managing subscription plans and subscribers in subscription/sql/functions.surql.

These changes streamline the messaging system by switching from RabbitMQ to NATS, update configuration settings, enhance documentation, and add new functionalities for managing subscriptions.