Use helm action client to render charts

[SimonBaeumer]

Currently the engine.Engine is used to render the chart under test. This has limited compatibilities, i.e. it does not resolve dependencies.
Using Helm's action client is closer to a real Helm chart upgrade/install/uninstall like one would do from the CLI.

[SimonBaeumer]

This code renderes the Helm chart and should be replaced with a call to the action client:

helmtest/pkg/framework/runner.go

Line 127 in cd13818

renderedTemplates, err := (&engine.Engine{}).Render(r.tgt.Chart, renderVals)

Helm action client which should be used: https://pkg.go.dev/helm.sh/helm/v3/pkg/action

[SimonBaeumer]

Goal is to test Helm charts with dependencies, installed CRDs etc