feat: configure watching options

[Kocal]

This PR adds support for properly configuring watching options.
References: #35, #126

Before, we had to do this:

const config = Encore.getWebpackConfig();

if (config.devServer) {
  config.devServer.watchOptions.poll = 250;
}

Now, we can do this:

Encore.configureWatchOptions(watchOptions => {
    watchOptions.poll = 250;
});

Also, I think it would be better to rename it to configureWatchOptions(), but I don't know how encore apply watching options to webpack when running dev or prod environment with encore [prod|dev] --watch. 🤔

Thanks!

---

EDIT: Ah, I found it!

I will see how can I modify watchOptions in dev/prod modes.

[Lyrkan]

Hi @Kocal,

Encore.configureDevServerWatchOptions() feels a bit long to me, configureWatchOptions() would probably be better imo.

That being said... I'm wondering if we shouldn't have a configureDevServer instead? Is watchOptions really that special to justify giving it its own method?

[Kocal]

Watch mode can be used without a dev-server, so I think it's better to have a .configureWatchOptions() methods that applies both for webpack and webpack-dev-server.

[Kocal]

What should I do with failing tests? It's working fine on local 😕

[Lyrkan]

Don't worry about the failing tests, they are not related to your PR :)

You don't have them locally because they are in a Travis job that tests the highest possible version of the dependencies (it removes the lock file before downloading them) and sometimes Webpack changes something that causes the hardcoded hashes from our functional tests to become outdated.

[Kocal]

Oh okay, thanks for the explanation 👍

[Kocal]

Who is ready for a new review? 😺

[Lyrkan]

Thank you @Kocal
As you can see in symfony/symfony-docs#10923 this was definitely needed :)

[Kocal]

Yep! :)