Add feature to scan barcode in camera frame to connect to barcode API

[jessechong]

Since we are leveraging Expo's many libraries, we are able to access the expo-camera library. See how we are using that API here: (#1)

Another very useful feature expo-camera has is the ability to scan barcode in the camera frame, without taking a picture. This should be connected to the barcode scanner API. See the expo-camera documentation here: (https://docs.expo.io/versions/latest/sdk/camera/)

I would particularly look at "onBarCodeScanned", "onBarCodeRead".