Properly pass in azure access token for flat file imports (#2750)

Co-authored-by: Lauren Nathan <laurennathan@microsoft.com>

Author: laurenastrid1

src/Microsoft.SqlTools.ServiceLayer/FlatFile/Contracts/ProseDiscoveryRequest.cs

@@ -69,6 +69,8 @@ public class InsertDataParams
         public string DatabaseName { get; set; }
 
         public int BatchSize { get; set; }
+
+        public string AzureAccessToken { get; set; }
     }
 
     public class InsertDataResponse

src/Microsoft.SqlTools.ServiceLayer/FlatFile/FlatFileService.cs

@@ -132,7 +132,7 @@ internal async Task HandleInsertDataRequest(
                         return await Task.Run(() => process.CreateTableAndInsertDataIntoDb(
                             connectionString,
                             parameters.BatchSize,
-                            null));
+                            parameters.AzureAccessToken));
                     });
                 if (!result.Success)
                 {