Function onDeviceChange

onDeviceChange(handler: () => void): () => void
Subscribes to device add/remove events (e.g. plugging in a headset).
Parameters
- handler: () => void
  Callback invoked whenever the device list changes.
Returns () => void
An unsubscribe function that removes the listener.
Example
```
const off = onDeviceChange(() => refreshDeviceList())
// later
off()
```
- Defined in media/src/MediaManager.ts:106