Health reporting

The RabbitMQ connector reports the readiness and liveness of each channel managed by the connector.

On the inbound side (receiving messages from RabbitMQ), the check verifies that the receiver is connected to the broker.

On the outbound side (sending records to RabbitMQ), the check verifies that the sender is not disconnected from the broker; the sender may still be in an initialized state (connection not yet attempted), but this is regarded as live/ready.