Add helm specific targets (redux)

A new MR that is the continuation of https://gitlab.com/ska-telescope/skampi/merge_requests/8 + fixes. It was reverted manually outside of the Gitlab flow so this new MR had to be created.

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Adding targets to the Makefile that allows us to use "Tillerless Helm" to manage charts.

Tillerless Helm is provided via third-party plugin in Helm v2, but is the defacto in Helm v3.

There are other changes to the CLI in Helm v3 that break our Makefile scripts so I've also created shims where I can for backwards compatibility.

This MR creates the following targets allow you to orchestrate things via Helm, particularly useful for Helm v2:

• helm_init: installs third-party helm-tiller plugin if on helm v2 and not already installed
• helm_deploy*: uses HELM_RELEASE and HELM_CHART to install the specified chart via helm, activating the helm-tiller plugin if on helm v2
• helm_test**: executes helm test against the provided HELM_RELEASE
• helm_delete**: will delete the given HELM_RELEASE
• helm**: allows you to run any helm command in the right context, e.g. make helm HELM_CMD="ls"

* invokes helm install with the --set tests.enabled=true so that charts with tests will deploy them.

** these are basically unecessary if you're using helm v3

Helm v2.16

Helm 3.0.0