chore: replace UglifyJs plugin by terser plugin

Replace "add-module-exports" Babel plugin by Webpack libraryExport.

.babelrc

@@ -3,8 +3,5 @@
     "modules": "commonjs",
     "corejs": "3",
     "useBuiltIns": "usage"
-  }]],
-  "plugins": [
-    "add-module-exports"
-  ]
+  }]]
 }

webpack.config.js

@@ -1,7 +1,6 @@
 // Webpack 4 configuration
 const path = require('path')
-const webpack = require('webpack')
-const UglifyJsPlugin = require("uglifyjs-webpack-plugin")
+const TerserPlugin = require('terser-webpack-plugin');
 const NotifierPlugin = require('webpack-build-notifier')
 
 var name = 'ima-ad-player'
@@ -10,14 +9,8 @@ var outputFile, plugins = [], optimization = {}
 if (process.env.npm_lifecycle_event === 'dist') {
   outputFile = name + '.min.js'
   optimization.minimizer = [
-    new UglifyJsPlugin({
-      cache: true,
-      parallel: true,
-      uglifyOptions: {
-        output: {
-          comments: false,
-        },
-      }
+    new TerserPlugin({
+      cache: true, // TODO: set to false if Webpack upgraded to 5.x ?
     }),
   ]
 } else {
@@ -35,6 +28,7 @@ module.exports = {
     path: path.resolve(__dirname, 'dist'),
     filename: outputFile,
     library: 'ImaAdPlayer',
+    libraryExport: 'default',
     libraryTarget: 'umd',
   },
   optimization: optimization,