Goal

• Add support for copy-ip-from, copy-ip-prefix-length-from in NMSTATE.
• As a Telco partner or customer, I want to retrieve the IP address and prefix length from a specific interface to create a customized br-ex using a templating approach. This must be supported even if no NMSTATE/NodeNetworkConfigurationPolicy (NNCP) has been previously applied (e.g., during cluster deployment).
• By using the requested options (copy-ip-from, copy-ip-prefix-length-from, and available option today, copy-mac-from), partners can use a single, unique configuration file applied across the entire cluster instead of maintaining a separate configuration for each node.

Context: create  customize-br-ex for several nodes (Telco use case) in the cluster during deployment time. ZTP/GitOps  as deployment method.

As you can see in the example below, we have a copy-mac-from, which copy the mac address of the interface (infra-bond.121) and set it on br-ex interface. This is working in current nmstate release.
We need options like below in nmstate to get ip and prefix and set it on a specific interface in our case  br-ex interface for IPV4 and IPV6.

- name: br-ex
  type: ovs-interface
  state: up
  copy-mac-from: infra-bond.121
  ipv4:
    enabled: true
    dhcp: false
    auto-route-metric: 48
    address:
      - copy-ip-from: infra-bond.121
        copy-prefix-length-from: infra-bond.121

Below the current implementation which need this same configuration file for each node in the cluster.

interfaces:
- name: br-ex
  type: ovs-bridge
  state: up
  ipv4:
    enabled: false
    dhcp: false
  ipv6:
    enabled: false
    dhcp: false
  bridge:
    options:
      mcast-snooping-enable: false
    port:
    - name: infra-bond.121
    - name: br-ex
- name: br-ex
  type: ovs-interface
  state: up
  copy-mac-from: infra-bond.121
  ipv4:
    enabled: true
    dhcp: false
    auto-route-metric: 48
    address:
      - ip: 192.168.121.18
        prefix-length: 25
  ipv6:
    enabled: false
    dhcp: false
routes:
  config:
    - destination: 0.0.0.0/0
      next-hop-address: 192.168.121.1
      next-hop-interface: br-ex
      table-id: 254
      advmss: 1400

Acceptance criteria

A list of verification conditions, successful functional tests, or expected outcomes in order to declare this story/task successfully completed.

• Verify IP address is copy and set to the target interface 
• Verify prefix-length is copy and set to the target interface