Move chargeback test resources to resources-folder

[nbokdam]

When setting up my workspace to contribute, I ran into an issue with the ChargebackResponseTest.

Problem

• JSON resources belonging to the test-cases were not included in my classpath when running unit tests;
• It seemed like IntelliJ by default only includes resources if they are in the resources-folder;

Solution

• Move the mentioned JSON-resources to the resources-folder;

I didn't bump the version, because it doesn't change any of the actual code. And I will put my name in the contributors-list in a separate PR, where I'll also make the actual contribution (and version bump). I'll be happy to change this if deemed necessary.

[nbokdam]

Nevermind, I noticed that I need to make a few other changes; let's minimize overhead and handle the test-fixes and actual change in 1 PR.