Modify the deployment script of JS SDK by following TypeScript's publishing guide

[hackerwins]

When I import Yorkie JS SDK from CodePair created with create-react-app with TypeScript enabled, I confirmed that it does not work properly.

./node_modules/yorkie-js-sdk/src/yorkie.ts 24:33
Module parse failed: Unexpected token (24:33)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
| //  e.g) yorkie.createClient(...)
| export default {
>   createClient: function (rpcAddr: string, opts?: ClientOptions): Client {
|     return new Client(rpcAddr, opts);
|   },

We need to modify the deployment script of JS SDK by following TypeScript's publishing guide.