Tekton Template for Jenkinsfile Runner

[oleg-nenashev]

It would be awesome to have a standard template for Tekton that allows easily running Jenkinsfile runner as a Tekton step.

Scope

• [ ] New repository for Tekton templates
• [ ] TBD: Better adaptation of Jenkinsfile Runner for Kubernetes deployments
• [ ] Tekton templates for vanilla Jenkinsfile runner and Image Packs that do not require configuration and image repackaging
• [ ] Tekton template for building Jenkinsfile Runner custom images, with help of Custom WAR Packager and YAML definitions. Depends on #570

Stakeholders

• Tekton community - TBD (@afrittoli)
• Jenkins X - TBD
• SAP as StewardCI developers/maintainers