Downlink Support

[htdvisser]

In the ingest pipeline:

• Processor: Extract downlink URLs and API key from the webhook headers:
  X-Downlink-Apikey, X-Downlink-Push, X-Downlink-Replace
• Processor: Store the downlink URLs and API key:
  ${net_id}/${application_id}.${device_id}@${tenant_id}.

Add a downlink pipeline:

• Input: Define Redis Stream, RabbitMQ topic/queue, MQTT topic for downlinks
• Processor: De-duplicate
• Processor: Load the downlink URLs and API key:
  ${net_id}/${application_id}.${device_id}@${tenant_id}
• Output: http_client

Add a processor pipeline:

• Input: Same as existing process
• Processor: If uplink has some specific fport/payload, generate a downlink
• Output: Downlink stream/topic