[Filebeat] Add health status reporting to Kafka input
Update the Kafka input to report its health status, providing better visibility into the operational state for users.
The Kafka input should report its health status using the context.UpdateStatus() method. Status changes should only be reported when the status actually changes (don't repeatedly send HEALTHY if the status is already HEALTHY).
Status Reporting
The input should report the following states:
- STARTING: TBD
- CONFIGURING: TBD
- HEALTHY: TBD
- DEGRADED: TBD
- FAILED: TBD
Include relevant context information with non-HEALTHY states:
- TBD
References
See the CEL input implementation for reference: https://github.com/elastic/beats/blob/6409d005a31e0147a40f0872794880b3df15a69c/x-pack/filebeat/input/cel/input.go#L111
Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)