NATS JetStream consumers and actor

[adzialocha]

After cleaning up the repository a bit and preparing it in https://github.com/HIRO-MicroDataCenters-BV/rhio/pull/53 this is the follow up PR, implementing an actor model for NATS JetStream, handling consumers.

This PR adds a nats module which holds an API and actor to handle JetStream consumers, filtered views on top of streams.

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:rocket:	This description was created by Ellipsis for commit 386af791df07980f9873588de957a70b969c359a

Summary:

This PR introduces a nats module with an actor model for NATS JetStream consumers, including a Nats struct with methods for initialization, subscription, and shutdown.

Key points:

• Adds nats module for NATS JetStream consumers.
• Implements actor model for handling consumers.
• Introduces Nats struct with methods for initialization, subscription, and shutdown.
• Implements Nats::new for client and actor initialization.
• Implements Nats::subscribe for consumer creation and message handling.
• Implements Nats::shutdown for actor shutdown signal.

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