Enable automatic code formatting for Java

### 🤔 What's the problem you've observed?

We currently don't automatically format our code.

This is not a big problem when I'm working on a Java project on my own as my IDE already applies a sensible style. And it seems that every one else can copy-paste the style just fine.

Still some small differences sneak in here and there.

### ✨ Do you have a proposal for making it better?

By enabling automatic code formatting we don't have to think about this anymore.

### 📚 Any additional context?

We are currently using [spotless](https://github.com/diffplug/spotless/tree/main/plugin-maven#google-java-format) in Cucumber-JVM. However this comes with [some custom settings](https://github.com/cucumber/cucumber-jvm/tree/main/.spotless) that would have to de (de-)duplicated somehow.