Feature: Implement Graceful shutdown

[werniq]

This PR introduces graceful shutdown functionality to the server. It ensures that the server properly handles shutdown signals (SIGINT, SIGTERM), stops accepting new requests, and allows ongoing requests to complete before shutting down. The update includes:

• A new Shutdown method to gracefully stop the server with a timeout.
• Signal handling in the Start and Run methods to listen for shutdown signals and trigger the graceful shutdown process.

This change enhances the server's stability by ensuring a smooth and controlled shutdown process.

[werniq]

@cebilon123 while repairing CI/CD I've noticed that some tests took really long. After some investigation, I've reached to rule package. I'm not sure, but I can't see any usage of it in the Waffle.

Is it needed? Or maybe it will be used later?

[werniq]

@thegodenage what about rule package? It is not used in project, but tests from this package are failing. Can I remove it too?

[werniq]

@thegodenage Finally, CI is blue 🙂

[werniq]

@thegodenage where can we chat about helm? There are few things that I would like to know, before implementing it.

[thegodenage]

@werniq Hey sure, sorry for late response, have a lot of different stuff in the meantime regarding daytime job and apartment.