producer ordered/unordered send

[bitcapybara]

• use a QUIC connection for each producer/consumer
• self-managed connection reconnect in producer/consumer
• self-managed connection pool in producer/consumer

[bitcapybara]

• BudClient
  * hold the connection info: broker address, etc.
  * has a get_connection method(connection manager)
  * clonable, hold by producer/consumer
• producer/consumer
  * get connection from client
  * setup reader/writer
  * reconnect

[bitcapybara]

• use one connection per client
• use Arc<Connection> from client in producer/consumer
• use a SharedError in producer/consumer to notify connection broken
• client reader hold a HashMap<consumer_id, unbounded_sender> for all consumers, after reconnect, send AddConsumer message to reader
• client sender hold event_tx to send AddConsumer/DelConsumer

[bitcapybara]

• consumer engine background task, receive message and send to consumer
• consumer receive message, poll by user