downloadFile: avoid connecting twice for each download on Android
downloadFile: avoid connecting twice for each download on Android

A connection already exists to fetch HTTP headers, so use that to complete the
download instead of making a second connection.

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