Java-based cfn-response module

[bdkosher]

Is your feature request related to a problem? Please describe.
There's a cfn-response module to support Lambda-backed AWS CloudFormation custom resources, but it's only available for Node and Python runtimes.

Describe the solution you'd like
A cfn-module equivalent for Java.

Describe alternatives you've considered
Lambda authors must create their own Java equivalent or use a supported runtime.

[msailes]

I think this would be helpful to customers, and it would save them a task.

Even better if we could then update the docs.

[heitorlessa]

cc @richardhboyd in case that's been discussed before somewhere else

[pankajagrawal16]

Released as part of https://github.com/awslabs/aws-lambda-powertools-java/releases/tag/v1.8.0