Add chrome.bluetooth and chrome.bluetoothLowEnergy for iOS

I also create a peripheral testing app that simply simulate BLE heart rate sensor, and I will add more to simulate other things for more tests.
https://github.com/oahziur/ble-tests-helper

I removed `chrome.bluetooth.startDiscovery` and `chrome.bluetooth.stopDiscovery` for iOS because I found that low energy devices can be found without calling them (which conflict with: https://developer.chrome.com/apps/app_bluetooth#le-discovery) on ChromeOS.
Not quite the intended purpose for callbackWithError. You're using it here strictly for it's console logging? Might be better to use your own helper here that just does the log (rather than having the helper throw & catch an exception)