[FEATURE] Support Layer 3 connectivity on user defined cluster network to act as underlay

[rrajendran17]

Is your enhancement request related to a problem? Please describe.

When using kubeovn, underlay Layer 3 connectivity is required for communication between VMs running on different nodes.
Currently Harvester has IP addresses configured only on mgmt interfaces, so kubeovn uses the mgmt-bo as underlay for communication between VMs running on different nodes.
Using same physical nic/nics part of mgmt-bo for VM traffic will impose traffic overhead as there is no segregation of VM traffic on a separate physical link.

Describe the solution you'd like
Allow configuration of IP Addresses on user configured cluster networks and utilising them as underlay for Layer 3 connectivity between nodes when using kubeovn

1.Create a cluster network
2.Create a vlanconfig spanning all nodes and select uplink
3.Allow users to provide ip range for underlay for the cluster network.
4.IP addresses must be assigned from the ip range to all the nodes in the cluster.
5.Allow users to select the user configured cluster network for the VM attached NAD and tweak kubeovn to use the user selected cluster network when using vxlan or communication between VMs running on different nodes.
(This has to be tested for feasibility)

By default br-int ovs bridge using mgmt-bo is used as ovs bridge for underlay connectivity

With this enhancement/feature, ovs bridge must be created for every user defined cluster network and vswitches/VMs lports must be attached to these ovs bridges based on the cluster network user defines for the NAD/subnet