The installer client should be able to register InfraEnv and ClusterDeployment independently. In assisted-service, this is called late binding, where the InfraEnv is created without any reference to a ClusterDeployment. At a later time when the ClusterDeployment is available the InfraEnv is then updated to add a reference to the ClusterDeployment.

Proposed change:

• Split InfraEnv registration into its own service: agent-register-infraenv.service
• Update agent-installer-client to create a new "register-infraenv" command.
• After the InfraEnv is created, the client waits for a ClusterDeployment to appear in assisted-service. The client updates the InfraEnv with a reference to the Cluster after the cluster is registered in assisted-service.
• After the InfraEnv is created, the clients looks for NMStateConfigs and host configs on the file-system. If present, it adds them to InfraEnv through the assisted-service REST-API.
• Update install-status.service and apply-host-config.service's dependency on create-cluster-and-infraenv.service to agent-register-infraenv.service.

Acceptance Criteria:

• InfraEnv can be registered without ClusterDeployment and AgentClusterInstall manifests
• After the InfraEnv is registered, the agents on each host can report back host validation to assisted-service (not sure if this is an actual requirement). Host validation can begin after the configuration ISO is mounted.
• Existing flow where both InfraEnv and ClusterDeployment manifests are available is unaffected
• Cluster installation is not started if only InfraEnv has been registered and ClusterDeployment has not
• NMStateConfigs and host configs are added to the InfraEnv if they exist on the file-system at the time the InfraEnv is created

This task is for modifying the client code in the assisted-service repo. A separate task will be created to represent changes needed to the installer, namely replacing create-cluster-and-infraenv.service with agent-register-infraenv.service and updating the dependencies of any existing agent services.