Integrate generate script with task service (#426)

* Support generate script for backup

* change

* update task service data contract for Generate Script

* more changes

* update test

* add comments

* Add missing files

* update stub backup operation for testing

* pr comments

* remove empty space

* Fix tests

* Add unit/integration tests and isCancelable to TaskInfo

* address pr comments

* pr comments - fix tests

* fix minor issue

* fix minor issues

* remove unused variable

src/Microsoft.SqlTools.ServiceLayer/TaskServices/Contracts/TaskInfo.cs

@@ -20,6 +20,11 @@ namespace Microsoft.SqlTools.ServiceLayer.TaskServices.Contracts
         /// </summary>
         public SqlTaskStatus Status { get;  set; }
 
+        /// <summary>
+        /// Task execution mode
+        /// </summary>
+        public TaskExecutionMode TaskExecutionMode { get; set; }
+
         /// <summary>
         /// Database server name this task is created for
         /// </summary>
@@ -30,7 +35,6 @@ namespace Microsoft.SqlTools.ServiceLayer.TaskServices.Contracts
         /// </summary>
         public string DatabaseName { get; set; }
 
-
         /// <summary>
         /// Task name which defines the type of the task (e.g. CreateDatabase, Backup)
         /// </summary>
@@ -52,5 +56,9 @@ namespace Microsoft.SqlTools.ServiceLayer.TaskServices.Contracts
         /// </summary>
         public string Description { get; set; }
 
+        /// <summary>
+        /// Defines if the task can be canceled
+        /// </summary>
+        public bool IsCancelable { get; set; }
     }
 }