Set up automation to push generated helm chart to chart repo

[mowies]

Goal

Set up pipelines to generate the helm chart from the kustomize overlay implemented in #600 and push the newly rendered chart into a separate helm chart repo.

Technical Details

• The new KLT helm chart repo should be set up as the helm docs suggest so that the repo can be used with the chart releaser action in the future
• The pipeline should update the appVersion on release of KLT (this can potentially be covered by Renovate)
• The pipeline should create a PR with changes (if there are any) on every push to KLT main branch

References

Helm chart releaser docs: https://helm.sh/docs/howto/chart_releaser_action/
Chart releaser action github repo: https://github.com/helm/chart-releaser-action

Depends on

• Test KLT helm chart with schedule #598

[odubajDT]

Pipeline for chart repository releasing helm charts on push to main branch available here:

https://github.com/odubajDT/helm-charts/

The repository contains a pipeline building and releasing the helm charts, an example helm-chart structure take from klt and a basic setup with required gh-pages branch

The second part of this issue -> creating a PR of changed helm-charts from keptn/lifecycle-toolkit repository (if there are any changes) against the charts repository will follow up