With the removal of UserManagedNetworking field (https://issues.redhat.com/browse/MGMT-15164), the user will need to be able to specify the platform field of the AgentClusterInstall to get the correct networking.

None platform indicates user managed networking

BareMetal platform indicates no user managed networking

1. Add platform as a customizable field in this template https://github.com/openshift-kni/cnf-features-deploy/blob/master/ztp/siteconfig-generator/siteConfig/clusterCRs.go#L21
   1. Reference CR for AgentClusterInstall https://github.com/openshift/assisted-service/blob/6d85fb16f8dd6ba3fa6c740fdf3fb4aed0acf329/docs/hive-integration/crds/agentClusterInstall.yaml#L13
2. Expose the field in SiteConfig so that it can be set by the user