Support for torch state checking

[halileohalilei]

The AVCaptureDevice API on iOS has a couple of methods like isTorchAvailable, isTorchActive and hasTorch for handling the torch. I haven't checked but I'm sure Android also has methods like these. It would be nice to see these methods implemented in react-native-torch, so that there would be no need for extra bridging to get the torch state from the native side.

[OlivierFreyssinet-old]

It would also be great to have support for something like onTorchModeChanged() https://developer.android.com/reference/android/hardware/camera2/CameraManager.TorchCallback.html#onTorchModeChanged(java.lang.String,%20boolean)

[oguennec]

@ludo, @OlivierFreyssinet and @halileohalilei , I have submitted this PR which adds a Torch getStatus functionality as requested in this thread.

[elrhomariyounes]

Please merge the @oguennec PR

[saberothmane]

@oguennec PR needed to merge please