Support hot-pluggable serial USB ports

[vortex314]

Describe the feature

I like a lot the concepts and the connectivity of zenoh , it solves a lot of challenges when you try to build a robotic model around pub/sub.
One of the things I try is to use an embedded linux server where the sensors and actuators are connected via USB. This makes it modular and easy composable. So the idea is to use the serial across USB. In linux these devices come and go as "/dev/ttyUSBx" or "/dev/ttyACMx". When I configure zenohd with a serial interface like below.

  listen: {
    endpoints: [
        "serial//dev/ttyUSB0#baudrate=115200"
      // "<proto>/<address>"
    ],
  },

The zenohd daemon fails to start as the device is not there yet.

[2024-02-21T18:52:13Z DEBUG mio_serial] opening serial port in synchronous blocking mode
[2024-02-21T18:52:13Z WARN  zenoh_link_serial::unicast] Can not create a new Serial link bound to "/dev/ttyUSB0": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:297.
[2024-02-21T18:52:13Z ERROR zenoh::net::runtime::orchestrator] Unable to open listener serial//dev/ttyUSB0#baudrate=115200: Can not create a new Serial link bound to "/dev/ttyUSB0": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:297.
Can not create a new Serial link bound to "/dev/ttyUSB0": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:297.. Exiting...

Is there a way to address this. As I want to avoid writing unnecessary proxies for zenoh.
Hope you can guide me further.

[vortex314]

Could be related - #712

[vortex314]

The issue doesn´t look to be solved :

   Compiling zenohd v0.11.0-dev (/home/lieven/workspace/zenoh/zenohd)
    Finished release [optimized] target(s) in 3m 37s
[2024-03-23T09:32:11Z INFO  zenohd] zenohd v0.11.0-dev-167-g3a264558 built with rustc 1.72.0 (5680fa18f 2023-08-23)
[2024-03-23T09:32:11Z INFO  zenohd] Initial conf: {"adminspace":{"permissions":{"read":true,"write":false}},"aggregation":{"publishers":[],"subscribers":[]},"connect":{"endpoints":[],"exit_on_failure":null,"retry":null,"timeout_ms":null},"downsampling":[],"id":"a12895a76d55c393f66b288ff6763619","listen":{"endpoints":["serial//dev/ttyUSB1#baudrate=115200","serial//dev/ttyUSB2#baudrate=115200","tcp/localhost:7447"],"exit_on_failure":null,"retry":null,"timeout_ms":null},"metadata":{"location":"Penny Lane","name":"strawberry"},"mode":"router","plugins":{},"plugins_search_dirs":[],"queries_default_timeout":10000,"routing":{"peer":{"mode":"peer_to_peer"},"router":{"peers_failover_brokering":true}},"scouting":{"delay":200,"gossip":{"autoconnect":{"peer":"router|peer","router":""},"enabled":true,"multihop":false},"multicast":{"address":"224.0.0.224:7446","autoconnect":{"peer":"router|peer","router":""},"enabled":true,"interface":"auto","listen":true},"timeout":3000},"timestamping":{"drop_future_timestamp":false,"enabled":{"client":false,"peer":false,"router":true}},"transport":{"auth":{"pubkey":{"key_size":null,"known_keys_file":null,"private_key_file":null,"private_key_pem":null,"public_key_file":null,"public_key_pem":null},"usrpwd":{"dictionary_file":null,"password":null,"user":null}},"link":{"protocols":null,"rx":{"buffer_size":65535,"max_message_size":1073741824},"tls":{"client_auth":false,"client_certificate":null,"client_private_key":null,"root_ca_certificate":null,"server_certificate":null,"server_name_verification":null,"server_private_key":null},"tx":{"batch_size":65535,"keep_alive":4,"lease":3000,"queue":{"backoff":100,"congestion_control":{"wait_before_drop":1000},"size":{"background":4,"control":1,"data":4,"data_high":2,"data_low":4,"interactive_high":1,"interactive_low":1,"real_time":1}},"sequence_number_resolution":"32bit","threads":2},"unixpipe":{"file_access_mask":null}},"multicast":{"compression":{"enabled":false},"join_interval":2500,"max_sessions":1000,"qos":{"enabled":false}},"shared_memory":{"enabled":true},"unicast":{"accept_pending":100,"accept_timeout":3000,"compression":{"enabled":false},"lowlatency":false,"max_links":10,"max_sessions":1000,"qos":{"enabled":true}}}}
[2024-03-23T09:32:11Z INFO  zenoh::net::runtime] Using PID: a12895a76d55c393f66b288ff6763619
[2024-03-23T09:32:11Z WARN  zenoh_link_serial::unicast] Can not create a new Serial link bound to "/dev/ttyUSB2": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:303.
[2024-03-23T09:32:11Z WARN  zenoh::net::runtime::orchestrator] Unable to open listener serial//dev/ttyUSB2#baudrate=115200: Can not create a new Serial link bound to "/dev/ttyUSB2": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:303.
Can not create a new Serial link bound to "/dev/ttyUSB2": No such file or directory at io/zenoh-links/zenoh-link-serial/src/unicast.rs:303.. Exiting...

even with config settings of retry , did I miss something ?

  listen: {
    endpoints: [
        "serial//dev/ttyUSB1#baudrate=115200;retry_period_init_ms=20000;retry_period_max_ms=10000",
        "serial//dev/ttyUSB2#baudrate=115200;retry_period_init_ms=20000;retry_period_max_ms=10000",
        "tcp/localhost:7447",
      // "<proto>/<address>"
    ],
  },