Add scripts that allow creation and teardown of AWS test setups

Testing changes to this plugin is currently quite hard if the developer doesn't have a running AWS setup.
We need a way to simplify the creation and also deletion of test setups in AWS so we can test changes to this plugin.

We could create [terraform](https://www.terraform.io/docs/providers/aws/index.html) scripts that will create all required resources in AWS and an empty VM where we can run Graylog with the AWS plugin. Terraform also provides a way to delete all resources again once testing is done.

Without something like this, it's really hard for developers and PR reviewers to actually test changes because it requires a lot of manual work.