splitEntryChunks() {
        webpackConfig.splitEntryChunks();

        return this;
    }
Tell Webpack to "split" your entry chunks.

This will mean that, instead of adding 1 script tag
to your page, your server-side code will need to read
the entrypoints.json file in the build directory to
determine the *multiple* .js (and .css) files that
should be included for each entry.

This is a performance optimization, but requires extra
work (described above) to support this.

@returns {Encore}