Add check port support

[kenichi-mashiyama]

Summary

This PR adds support for configuring a dedicated health check port (check port <number>) for servers across backends and listens.

Motivation

Currently, when health checks are enabled, HAProxy Operator defaults to using the same port as the server's traffic port for health checks. However, some applications expose a separate, dedicated port for health checks or metrics (e.g., application traffic on port 8080, but health checks on port 80). By adding the port field to the Check struct, users can now explicitly specify a different port for health checks directly through the CRDs.

Changes

• Added the Port (*int64) field with validation (min: 1, max: 65535) to the Check struct in apis/config/v1alpha1/common_types.go.
• Updated the Model() methods for Server and ServerTemplate to map this new field to the native HAProxy model (model.HealthCheckPort).
• Added a unit test in apis/config/v1alpha1/backend_types_test.go to verify the correct generation of the check port <number> configuration on the server line.
• Regenerated CRDs, DeepCopy methods, and API documentation to reflect the schema updates.

Checklist

• Code changes implemented
• Unit tests added/updated
• Generated CRDs and API docs updated