Streamlined BLE Device Scanning Process

[oleander]

This PR simplifies the BLE device scanning process.

Before:

let connect_device = Arc::new(Mutex::new(None));
let device0 = connect_device.clone();
scan.on_result(move |scan, device| {
  if device.name().contains("ESP32") {
    scan.stop().unwrap();
    (*device0.lock()) = Some(device.clone());
  }
});

scan.start(10000).await.unwrap();
let device = &*connect_device.lock();
if let Some(device) = device {
  info!("Advertised Device: {:?}", device);
}

After:

scan.on_result(|device| {
  if device.name().contains("Shelly") {
    Some(device)
  } else {
    None
  }
});

if let Some(device) = scan.start(10000).await.unwrap() {
  info!("Advertised Device: {:?}", device);
}

The device returned by on_result is the return value for start. I removed the scan argument to on_result, but I'm happy to add it again.

I'm open to suggestions on how to improve the scan API further :)

[taks]

Thanks for sending a pull request.
I think your proposal is good, but there are situations where scan is used other than to acquire a device.

Therefore, instead of changing existing functions, how about adding one more find_device function as shown below?

let result = scan.find_device(1000, |device| device.name().contains("Shelly")).await.unwrap();

if let Some(device) = result {
  info!("Advertised Device: {:?}", device);
}

[oleander]

find_device is a good idea! I updated the code accordingly.

[taks]

Thanks for the change.