Optional-Test-Infra Beta Stage Development

[PatrickXYS]

Below list is the development list of AWS CI beta stage.

1. Migrate from ksonnet-based Argo Workflow to Tekton
2. To migrate to Tekton, we need to install / configure Tekton on Shared Test-infra
3. Provide uniform scripts and enforce WG to use scripts, sacrifice some flexibility to obtain better availability / management.
4. Research release infra, which is CD pipeline.
5. Divide test-infra into Production and Development environment, every change need to be tested on development env first, then deploy to production. This might slow down development speed, but I think it's necessary if WG want to use shared test-infra. Otherwise, they might need to find preferred solution.
6. Automate Webhook Management #354
7. Existing kfctl + manifests are expensive and flaky, need to be more modular and stable
8. Generating Kubeflow + Kubernetes Compatibility Matrix
9. Expose Shared Test-infra configuration
10. Testing Image CD
11. Upgrade testing image dependencies #779
12. Two bots screaming in the same PR if user calls /retest