Verify list_hypervisors_detail Nova V2/V3 API

This patch adds the JSON Schema for response of Nova V2 & V3
list hypervisor detail API and validate the response with added
JSON Schema to block the backward incompatibility change in the future.

The response body of V2 list hypervisor detail API is below:

{
    "hypervisors": [
        {
            "cpu_info": "?",
            "current_workload": 0,
            "disk_available_least": null,
            "host_ip": "%(ip)s",
            "free_disk_gb": 1028,
            "free_ram_mb": 7680,
            "hypervisor_hostname": "fake-mini",
            "hypervisor_type": "fake",
            "hypervisor_version": 1,
            "id": 1,
            "local_gb": 1028,
            "local_gb_used": 0,
            "memory_mb": 8192,
            "memory_mb_used": 512,
            "running_vms": 0,
            "service": {
                "host": "%(host_name)s",
                "id": 2
            },
            "vcpus": 1,
            "vcpus_used": 0
        }
    ]
}

The response body of V3 list hypervisor detail API is below:

{
    "hypervisors": [
        {
            "cpu_info": "?",
            "current_workload": 0,
            "disk_available_least": 0,
            "host_ip": "%(ip)s",
            "free_disk_gb": 1028,
            "free_ram_mb": 7680,
            "hypervisor_hostname": "fake-mini",
            "hypervisor_type": "fake",
            "hypervisor_version": 1,
            "id": %(hypervisor_id)s,
            "local_gb": 1028,
            "local_gb_used": 0,
            "memory_mb": 8192,
            "memory_mb_used": 512,
            "running_vms": 0,
            "service": {
                "host": "%(host_name)s",
                "id": 2
            },
            "vcpus": 1,
            "vcpus_used": 0,
            "os-pci:pci_stats": []
        }
    ]
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I0815ecf1dc985ba404f636a68dccbbf6be4188d5
Merge "Verify list_hypervisors_detail Nova V2/V3 API"