ncm-network: option to not manage interface using ncm

[aka7]

We have FPGA interfaces defined in Aquilon as network interfaces but would like to not have them configured by the OS as they will not present actual ethX devices to the OS so that we can still track (/system/network) and manage FPGA network configuration through aquilon but not have ncm-network /nmstate managing it. FPGA interfaces would be defined as normal Aquilon interfaces (so they still appear under /system/network) but with this flag set.
would it be possible to update schema to perhaps have a flag if defined and set to false to indicate they shouldn't be configured in the OS.
so

• Schema update to support this new config option
• ncm-network update to skip configuring interfaces with this option set