add xms-ids for migrate (Azure#17821)

Author: LinglingTong

specification/migrate/resource-manager/Microsoft.Migrate/stable/2019-10-01/migrate.json

@@ -1939,6 +1939,9 @@
           "items": {
             "$ref": "#/definitions/CloudErrorBody"
           },
+          "x-ms-identifiers": [
+            "code"
+          ],
           "description": "A list of additional details about the error."
         }
       },
@@ -2218,7 +2221,10 @@
           "readOnly": true,
           "items": {
             "$ref": "#/definitions/VmFamily"
-          }
+          },
+          "x-ms-identifiers": [
+            "familyName"
+          ]
         },
         "reservedInstanceVmFamilies": {
           "type": "array",
@@ -2308,7 +2314,10 @@
           "description": "List of operations.",
           "items": {
             "$ref": "#/definitions/Operation"
-          }
+          },
+          "x-ms-identifiers": [
+            "name"
+          ]
         }
       }
     },