Set up TypeScript Environment

[zaki-yama]

ref. #289

Construct TypeScript environment.
In addition to transpile to current ES5 format (with babel-preset-env), we need to build as ES Modules format so that the users can use Tree-shaking with webpack, Rollup, etc.

TODO

• Update Babel's version to 7 to support TypeScript > Setup TypeScript Environment #291
• Enable to transpile .ts files to ES5 format > Setup TypeScript Environment #291
• Update React version > Update React to v16 #292
• Update ESLint version > Update ESLint #293
• Introduce Prettier > Introduce Prettier #294
• Update Storybook version to v5 > Update Storybook to v5 #297
• Enable to use ESLint with TypeScript > ESLint: Configuration for TypeScript #298
• Enable to run Jest > 287f01b in Rewrite in Typescript: ButtonGroup #303
• Enable to transpile .ts files to ES Modules format
• Enable to run Storybook