Automatically get VIP during PXE installation

• Related issues: #1410 Support getting VIP automatically during PXE boot installation

Verification Steps

1. Comment vip and vip_hw_addr in ipxe-examples/vagrant-pxe-harvester/ansible/roles/harvester/templates/config-create.yaml.j2
2. Start vagrant-pxe-harvester
3. Run kubectl get cm -n harvester-system vip
   • Check whether we can get ip and hwAddress in it
4. Run ip a show harvester-mgmt
   • Check whether there are two IPs in it and one is the vip.

Expected Results

1. VIP should automatically be assigned