Cache busting for CSS files

(cherry picked from commit 38f263931ff8faba050762abe5fb692a5bc0d515)

frontend/build/webpack.config.js

@@ -91,7 +91,8 @@ module.exports = (env) => {
       }),
 
       new MiniCssExtractPlugin({
-        filename: 'Content/styles.css'
+        filename: 'Content/styles.css',
+        chunkFilename: 'Content/[id]-[chunkhash].css'
       }),
 
       new HtmlWebpackPlugin({