Create Keptn Argo REST client

[mowies]

Goal

Deploy the Keptn REST API backend using normal k8s operator practices (reconcile loops) and add the corresponding feature flag to the KeptnConfig resource.

Notes

new feature flag in keptn config
lifecycle operator deploys REST API based on feature flag
API has a kube client with read/list permissions to all keptn resources (basically)

Tasks

Beta Give feedback

1. Add Keptn/Argo REST API client feature flag to KeptnConfig #3594
   status: in-progress +1
   
2. Boilerplate setup #3595
   status: in-progress +1
   
3. Deploy Keptn client using lifecycle operator reconcile loop #3596
   status: in-progress +1
   
4. Follow up
5. Introduce configuration options for Keptn client in KeptnConfig #3597
   +0