side-effect-free-webpack-stat-plugin

Add side effect free flags to webpack build stats

$3

``bash
npm i --save-dev side-effect-free-webpack-stat-plugin
`

$3

in webpack.config.js
`js
const SideEffectFreeWebpackStatPlugin = require('side-effect-free-webpack-stat-plugin');
module.exports = {
plugins: [new SideEffectFreeWebpackStatPlugin()],
stats: {
modules: true
}
};
`

then in stats.json in each module will be 2 fields:
- sideEffectFreeModule will be true if module is side effect free due to sideEffects flag
- sideEffectFreeContent will be true if module code is side effect free, null` for unknown state (webpack did not require to check this)