DBaaS: Ability to specify the type of connection for DBaaS cluster during DB Cluster creation

User story:
When I creating a DB cluster I need to be able to specify the type of connection (internal/external) I need for the particular DB Cluster, so that access to the cluster is controlled

UI/UX:
? "Step2": Connection select/checkbox to let user set it external or internal
TBD

Acceptance criteria

• The user is able to specify the type of the connection during the cluster creation process
• User is getting the type of connection he/she requested
• When looking at the list of Clusters user is able to see is this externally available or internal only DB cluster
• The default value for EKS/GKS based clusters should be  "internal"
• Documentation
  • RN
  • DbaaS usage documentation updated with an explanation about internal/external connections and differences with them

Out of scope:

• other operations
• other than specifying it during the creation and view on the list
• GKS is not yet supported/tested 

Suggested implementation:
TBD

How to test:
TBD

Details:
TBD

Original report:
As a user creating a database and my Kubernetes orchestrator is one of the public cloud providers (EKS/GKS/etc), my database should not become world-public automatically but instead remain private by default or issue a public load balancer IP only if I request it.  This could cause severe harm to my business if in inadvertently open up a system for world access with a weak account causing me to incur heavy processing/consumption costs.  

Therefor if I'm a entirely on private infrastructure (including my K8s layer) I would have the option to make my DBaaS instance private to K8s (no external load-balanced IP) or public to my network.  But if I'm found to be using public cloud for K8s, I would expect an additional option to make it public to the world but that option would be off by default.