Add optional param - private DNS zone to MySQL server API (#14964)

* add optional parameter private dns zone to server create/update

* fix lintdiff errors

* fix prettier issues

Author: shih-che

specification/mysql/resource-manager/Microsoft.DBforMySQL/preview/2020-07-01-preview/examples/ServerGet.json

@@ -38,9 +38,6 @@
             "startHour": 0,
             "startMinute": 0,
             "customWindow": "Disabled"
-          },
-          "delegatedSubnetArguments": {
-            "subnetArmResourceId": "/subscriptions/ffffffff-ffff-ffff-ffff-ffffffffffff/resourceGroups/testrg/providers/Microsoft.Network/virtualNetworks/test-vnet/subnets/test-vnet-subnet"
           }
         },
         "location": "westus",

specification/mysql/resource-manager/Microsoft.DBforMySQL/preview/2020-07-01-preview/examples/ServerGetWithVnet.json

@@ -32,6 +32,9 @@
           "haEnabled": "Disabled",
           "delegatedSubnetArguments": {
             "subnetArmResourceId": "/subscriptions/ffffffff-ffff-ffff-ffff-ffffffffffff/resourceGroups/testrg/providers/Microsoft.Network/virtualNetworks/test-vnet/subnets/test-vnet-subnet"
+          },
+          "privateDnsZoneArguments": {
+            "privateDnsZoneArmResourceId": "/subscriptions/ffffffff-ffff-ffff-ffff-ffffffffffff/resourceGroups/testrg/providers/Microsoft.Network/privateDnsZones/test-private-dns-zone"
           }
         },
         "location": "westus",

specification/mysql/resource-manager/Microsoft.DBforMySQL/preview/2020-07-01-preview/mysql.json

@@ -1538,6 +1538,16 @@
       },
       "description": "Delegated subnet arguments of a server"
     },
+    "privateDnsZoneArguments": {
+      "type": "object",
+      "description": "Private DNS zone arguments of a server",
+      "properties": {
+        "privateDnsZoneArmResourceId": {
+          "type": "string",
+          "description": "private dns zone arm resource id."
+        }
+      }
+    },
     "MaintenanceWindow": {
       "type": "object",
       "description": "Maintenance window of a server.",
@@ -1769,6 +1779,10 @@
           "$ref": "#/definitions/DelegatedSubnetArguments",
           "description": "Delegated subnet arguments."
         },
+        "privateDnsZoneArguments": {
+          "$ref": "#/definitions/privateDnsZoneArguments",
+          "description": "private dns zone arguments."
+        },
         "createMode": {
           "type": "string",
           "description": "The mode to create a new MySQL server.",