[Testing][Kubernetes] Provide test coverage for ServiceCatalog

JBoss Community

Tests should be written in JUnit 5
Provide comments where necessary
Basic test methods to be included are testList(), testGet(), testDelete(), testLoadFromFile()
Changes are to be documented in CHANGELOG.md
Take reference from https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-tests/src/test/java/io/fabric8/kubernetes/client/mock/PodTest.java

Skyterix