Add liveness and readiness probes

[jpcorreia-promptly]

This pull request introduces health check endpoints to the service, allowing readiness and liveness probes for deployment and monitoring purposes. The service is considered ready only after all presets are loaded.

Health check endpoints and readiness tracking:

• Implemented HealthModule.kt with routes for /health/ready (returns 200 if validation service is ready, 503 otherwise) and /health/live (always returns 200 if service is running).
• Added /health/ready and /health/live endpoints to the OpenAPI specification in openapi.yml, documenting their responses and intended use for readiness and liveness probes.

Validation service readiness management:

• Added ValidationServiceStatus.kt to track the readiness of the validation service using an atomic reference, with methods to set the service and check readiness.
• Updated ValidationServiceFactoryImpl.kt to set the validation service in ValidationServiceStatus after presets are loaded, ensuring readiness is accurately reported.

[jpcorreia-promptly]

@dotasek, @markiantorno, could you please review this?