add x-ms-enum for sql (Azure#17028)

* add x-ms-enum for sql

* fix to make sure track 1 generator is happy

Author: ArcturusZhang

specification/sql/resource-manager/Microsoft.Sql/preview/2020-11-01-preview/BlobAuditing.json

@@ -1050,6 +1050,10 @@
       "enum": [
         "default"
       ],
+      "x-ms-enum": {
+        "name": "BlobAuditingPolicyName",
+        "modelAsString": false
+      },
       "x-ms-parameter-location": "method"
     }
   },

specification/sql/resource-manager/Microsoft.Sql/preview/2020-11-01-preview/SyncGroups.json

@@ -222,7 +222,11 @@
               "Error",
               "Warning",
               "Success"
-            ]
+            ],
+            "x-ms-enum": {
+              "name": "SyncGroupsType",
+              "modelAsString": true
+            }
           },
           {
             "name": "continuationToken",