This commit updates all library and plugin dependencies
in the `spring-cloud-dataflow-apps-plugin` modules to
the latest versions.
Additionally:
- performs a general cleanup of build and README files.
- updates to maven 3.9.9
Resolves#498
* Address code review comments:
- Use `1.1.0-SNAPSHOT` as version in metadata plugin README.adoc
to be consistent w/ other examples