Convert legacy docker tests from bash to Golang

[dereknola]

Is your feature request related to a problem? Please describe.
The current docker tests use a complex series of bash function hooks to construct k3s cluster out of docker containers, using the rancher/k3s image we publish. These tests are difficult to read, difficult to write, and do not match the ginkgo/gomega centric BDD testing frameworks we have constructed for integration and E2E tests.

Describe the solution you'd like
Convert the old docker tests to use Ginkgo/Gomega BDD testing framework. This framework will likely be similar but separate from E2E and Integration frameworks. Future work could potentially combine all 3 frameworks where it makes sense.