DBaaS: Simplify K8s preparation by installing all available operators

The goal:

• Simplify the UX for preparation of K8s

• Avoid manual actions for users when they have just K8s config and empty K8s

User story:

• As a DBaaS admin, I need to be able to use K8s Cluster in PMM by providing credentials (kubeconfig) to K8s empty cluster, so that I don't need any additional manual actions to create DB clusters inside it  

UI/UX: 

• Current UI to register K8s cluster (provide kubeconfig) 

• **

Acceptance criteria:

• User able to register empty k8s cluster 

Out of scope: 

• operator upgrade 

Suggested implementation:
TBD

How to test:
TBD

Details:
TBD

Out of scope:

• Create K8s cluster on Cloud provider. The user still need to provide kubeconfig