Update RNFSManager Android file to handle append in the writeFile method.
Update RNFSManager Android file to handle append in the writeFile method.

johanneslumpe/react-native-fs,itinance/react-native-fs,itinance/react-native-fs,johanneslumpe/react-native-fs,johanneslumpe/react-native-fs,itinance/react-native-fs,itinance/react-native-fs