Load Balancer setup may demand more complex configurations

There are two main improvements I can see for Azure LBs:

1) We do not have any way to specify a private VIP:

Although it is possible to set an ingress-address in the requests, azure-integrator does not pick this information up.

2) LBs should be able to specify subnet IDs:

There are some scenarios where we want to deploy a LB in RG A, while network and subnets are available in RG B.

That means we need to run a command similar to:

azure network lb create --resource-group <rg-where-backend-is> --subnet <entire-id-of-subnet>

In this case, no vnet-name should be provided. Therefore, we need a second option where one can specify the subnetID instead of subnetName.