Use smartStrategy to replace loaders with preset (#2084)

Using `merge.smartStrategy` with `'module.loaders' = 'replace'` to load
the preset config allows presets to override the the default webpack
config. This is necessary for the coming Tailwind preset which requires
`resolve-url-loader` and source maps to be disabled.

resources/assets/build/webpack.config.js

@@ -214,4 +214,6 @@ if (config.enabled.watcher) {
   webpackConfig = merge(webpackConfig, require('./webpack.config.watch'));
 }
 
-module.exports = merge(webpackConfig, desire(`${__dirname}/webpack.config.preset`));
+module.exports = merge.smartStrategy({
+  'module.loaders': 'replace',
+})(webpackConfig, desire(`${__dirname}/webpack.config.preset`));