Function heartbeat_task 

pub async fn heartbeat_task(
    shutdown: CancellationToken,
    client: Arc<dyn SignalingClient>,
    actor_id: ActrId,
    credential_state: CredentialState,
    mailbox: Arc<dyn Mailbox>,
    heartbeat_interval: Duration,
)

Heartbeat task that periodically sends Ping messages to signaling server

This task runs in a loop, sending heartbeat messages at the specified interval and handling Pong responses, including credential warnings.

Arguments

• shutdown - Cancellation token for graceful shutdown
• client - Signaling client for sending heartbeats
• actor_id - Actor ID for heartbeat messages
• credential_state - Shared credential state
• mailbox - Mailbox instance for backlog statistics
• heartbeat_interval - Interval between heartbeats