Manually trigger alert

Manually triggers an alert to test its functionality and notification delivery. Useful for testing alert configurations, verifying notification channels, and ensuring alerts work as expected before relying on them for monitoring. When a destination or the on-call page could not be delivered, the response also carries warning with the reason. For an anomaly detection alert it runs detection now and returns message, claim_lost, ineligible, anomaly_id, anomalies_found, points_scored and anomalies; claim_lost: true means another detection run for this alert is in progress, and ineligible: true means the detector is disabled or untrained (message says which), so nothing was scored.