Register domain with specific namespace and target to router

[p1c2u]

Describe the bug

It's possible to register domain that points to specific namespace and service or specific router but not both.

To Reproduce

rio domain register  myproductionsite.com default:router/prod

we get

Spec:
  Target App:        router/prod
  Target Namespace:  default

Expected behavior
It should be:

Spec:
  Target Namespace:  default
  Target Router:     prod

Kubernetes version & type (GKE, on-prem): kubectl version

Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.3", GitCommit:"1e11e4a2108024935ecfcb2912226cedeafd99df", GitTreeState:"clean", BuildDate:"2020-10-14T12:50:19Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.9+k3s1", GitCommit:"630bebf94b9dce6b8cd3d402644ed023b3af8f90", GitTreeState:"clean", BuildDate:"2020-09-17T19:05:07Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"linux/amd64"}

Type:
Rio version: rio info

Rio Version: v0.8.0 (af7ad687)
Rio CLI Version: v0.8.0 (af7ad687)
Cluster Domain: xxx
Cluster Domain IPs: xxx
System Namespace: rio-system
Wildcard certificates: xxx(true)

Additional context
rio system logs
output: