Simplify step handler and date formatting in BatchJobExecutionResourceDefinition

org.wildfly.extension.batch.jberet.deployment.BatchJobExecutionResourceDefinition currently defines various anonymous inner classes to deal with create-time, start-time, end-time, update-time. They can be simplified with appropriate method pointers.

These step handlers currently format these date values with SimpleDateFormat, creating one instance of it for each operation. This is not efficient and can be replaced with java.time.DateTimeFormat.