Refs
  #13272 (comment)
  reactjs/rfcs#38

In this PR I modified build script to generate two more bundles
`react-is.development.mjs` and `react-is.production.min.mjs` and
entry point `index.mjs` which reexports all named values depending on
production/development environments like this

```
import * as dev from './esm/development.mjs'
import * as prod from './esm/production.min.mjs'

export var name =
  process.env.NODE_ENV !== 'production' ? dev.name : prod.name;
```

I replaced closure wrapper with vendor plugin which is able to process
es modules by replacing them before and returning them after closure
minification.

To prove treeshakability of dual entry point we can generate rollup
bundle with `import {} from 'package'`. If nothing will left then
user bundler is able to eliminate unused code from dual entry point.