enableHandlebarsLoader(callback = () => {}) {
        webpackConfig.enableHandlebarsLoader(callback);

        return this;
    }
Call this if you plan on loading Handlebars files.

```
Encore.enableHandlebarsLoader();
```

Or pass options to the loader

```
Encore.enableHandlebarsLoader(function(options) {
    // https://github.com/pcardune/handlebars-loader
    // options.debug = true;
});
```

@param {OptionsCallback<object>} callback
@returns {Encore}