Remove unnecessary dependencies from the metadata plugin

[sabbyanandan]

We will have to redesign the plugin so that it doesn't have a hard requirement on the following dependencies. Having them in the classpath, might have a conflict with custom apps that also rely on similar or related dependencies.

https://github.com/spring-cloud/spring-cloud-dataflow-apps-plugin/blob/bbb5edac05810e9bc3ef34fb28bd1744b0fdaccc/spring-cloud-dataflow-apps-metadata-plugin/pom.xml#L46-L90

To make this plugin usable by the community/customers, we must design it to not rely on these dependencies.