added `imwrite` and `imwriteSync`
added `imwrite` and `imwriteSync`

- changed `HybridAsyncWorker.GetResult` to return `undefined` by default
- split `ReadImageAsyncWorker` and `DecodeImageAsyncWorker`
- moved all code info package into namespace ncv::imgcodecs

akshonesports/node-opencv,akshonesports/node-opencv,akshonesports/node-opencv,akshonesports/node-opencv,akshonesports/node-opencv,akshonesports/node-opencv,akshonesports/node-opencv