Add default methods in interfaces

[fmbenhassine]

Several core interfaces could benefit from using Java 8's default methods in interfaces feature. This has a couple of advantages:

• It makes client code more readable as it does not require it to implement all methods of a given interface.
• It reduces the code on the framework side since support classes (like JobExecutionListenerSupport, StepExecutionListenerSupport, ChunkListenerSupport, etc) become obsolete in favour of default methods.

This feature is similar to what has been done in other projects (Here is an example from Spring Framework) and the goal is to make sure the Spring (Batch) developer has a consistent experience across the portfolio.

[parikshitdutta]

Hi @benas, I am on it, Please assign this one and it's dependent #3925 to me.

Thank you.

[parikshitdutta]

Hi @benas, please review PR #3934. I will look forward to your feedback.

Thank you.