Refactor module (loader) rules

- Removed unnecessary url-loader targeting .woff files
- Replaced file-loader with url-loader (file is fallback for url)
- PostCSS plugins are all loaded manually vs postcss.config.js

resources/assets/build/webpack.config.optimize.js

@@ -1,23 +1,12 @@
 'use strict'; // eslint-disable-line
 
-const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');
 const { default: ImageminPlugin } = require('imagemin-webpack-plugin');
 const imageminMozjpeg = require('imagemin-mozjpeg');
-const cssnano = require('cssnano');
 
 const config = require('./config');
 
 module.exports = {
   plugins: [
-    new OptimizeCssAssetsPlugin({
-      cssProcessor: cssnano,
-      cssProcessorOptions: {
-        discardComments: { removeAll: true },
-        autoprefixer: {},
-        safe: true,
-      },
-      canPrint: true,
-    }),
     new ImageminPlugin({
       optipng: { optimizationLevel: 7 },
       gifsicle: { optimizationLevel: 3 },