Support configuring a VLAN at the management interface in installer config

Ref: https://github.com/harvester/harvester/issues/1390, https://github.com/harvester/harvester/issues/1647

Verify Steps:

1. Install Harvester with any nodes from PXE Boot with configurd vlan with vlan_id
2. Harvester should installed successfully
3. Login to console, execute ip a s dev mgmt-br.<vlan_id> should have IP and accessible
4. Dashboard should be accessible