* Remove redundant import.
* Simplify sample_test.yaml by using withItem syntax.
* Simplify sample_test.yaml by using withItem syntax.
* Change dict to str in withItems.
* Add image pull secret sample.
* Move imagepullsecret sample from test dir to sample dir. Waiting on corresponding unit test infra refactoring.
* Update the location of imagepullsecrets so that it can serve as an example.
* Add minimal comments documenting usage.