Add S3 ItemReader/Writer Single-step job

[sabbyanandan]

SCDF users would like to have included in the OOTB app.

Depends on https://github.com/spring-projects/spring-batch/issues/3818.

[making]

+1

In SCDF on cloud platforms, reading/writing S3 (compatible object storage) is much more important than local file system (file://).

but having the dependency on spring-cloud-aws only for S3 is too much. It also pulls extra features. Using Minio SDK would be better for this purpose. https://docs.min.io/docs/java-client-api-reference.html