/*Scans for available wifi networks. Async.
* You must return early (< 10ms) for this function call.
* Keep the reference to the isDone variable in your local storage.
* the isDone variable signals to this interface that your device is still busy.
* When the wifi scan is done, you should set isDone to true.
* When this method is called, you may free any results from a previous wifi scan.
* If an internal error or something else leads to the wifi scan not being able to complete, set isDone to true as well.