Add gRPC Health Checking Protocol support

## Summary
Add support for the standard gRPC Health Checking Protocol (`grpc.health.v1`) to Tracee's gRPC server.

## Motivation
Tracee exposes health checks only via HTTP `/healthz`. Adding the standard gRPC health service enables:
- Native Kubernetes gRPC health probes (stable since v1.24)
- Compatibility with `grpcurl` and `grpc-health-probe`
- gRPC load balancer health checks

## References
- [gRPC Health Checking Protocol](https://github.com/grpc/grpc/blob/master/doc/health-checking.md)
- [Kubernetes gRPC Probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-a-grpc-liveness-probe)

Start by locating Tracee's gRPC server and the existing HTTP /healthz implementation. Read the referenced gRPC Health Checking Protocol and verify the result with grpcurl or grpc-health-probe; done means the standard grpc.health.v1 service is available for Kubernetes probes and gRPC clients.

Written by the indexing model from the issue text.