Load Balancer API Updates for the Terraform Provider

This commit tweaks some of the endpoints to accommodate Terraform Provider implementation in an easier way. It also contains an additional PATCH endpoint which is a much better approach than implementing individual resource types to handle /attach-vm /detach-vm endpoints. Another change is using the vm ubids in an array form instead of serializing multiple VMs in the response body for a load balancer. It is still used in the WEB endpoints but not in the APIs.