Add Unit Tests for the chart

[taylorsilva]

We have a lot of pain with running topgun/k8s. It would be great to eliminate or greatly reduce it's coverage to strictly integration-level tests only. Most things we want to test can probably be covered by a set of unit tests.

Helm itself does not have a unit testing framework but the community has made a tool to cover this need, helm-unittest

The original helm-unittest project is not maintained (https://github.com/lrills/helm-unittest) but this fork has become the main fork people are contributing to: https://github.com/quintush/helm-unittest