[DataFactory]Support Dataset and LinkedService for Rest call transform (Azure#16394)

* update

* update

Author: kesharma

specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/entityTypes/DataFlow.json

@@ -214,6 +214,14 @@
           "description": "Transformation description.",
           "type": "string"
         },
+        "dataset": {
+          "description": "Dataset reference.",
+          "$ref": "../datafactory.json#/definitions/DatasetReference"
+        },
+        "linkedService": {
+          "description": "Linked service reference.",
+          "$ref": "../datafactory.json#/definitions/LinkedServiceReference"
+        },
         "flowlet": {
           "description": "Flowlet Reference",
           "$ref": "../datafactory.json#/definitions/DataFlowReference"