Provider network support when OVN is used

Some workloads (VMs/containers) are expected to be using provider networks in addition to OVN virtual networks.

OVN does provide a way to connect to provider networks using Gateway router.

This feature is expected to work with multiple provider networks.

It should be possible for a workload to sit on multiple provider networks.

Work items:

• A way to create provider networks (To be done as part of KRD? - One Gateway per provider network?)
• A way to discover provider networks
• A way to define that workload need to be placed in various provider networks (make it as generic as possible)