This reverts commit 40e0037d50.
It doesn't build on Android:
> Task :react-native-reanimated:buildCMakeRelWithDebInfo[arm64-v8a] FAILED
C/C++: ninja: error: '../../../../build/third-party-ndk/hermes/jni/arm64-v8a/libhermes.so',
needed by '../../../../build-main/intermediates/cxx/RelWithDebInfo/6w4f694p/obj/arm64-v8a/libreanimated.so',
missing and no known rule to make it
Since the RNFetchBlob API doesn't support writing binary data directly
it creates a custom Writable which is doing the base64 encoding per
chunk.
This also fixes a problem with the S3 synchronization code using the
shim.fsDriver().writeBinaryFile().
Tested with AVD Android 10.0 target.
Signed-off-by: Jan Blunck <jblunck@users.noreply.github.com>