Progressive Results Part 2: Result Completion Event (#134)

The main change in this pull request is to add a new event that will be fired upon completion of a resultset but before the completion of a batch. This event will only fire if a resultset is available and generated.

Changes:
* ConnectionService - Slight changes to enable mocking, cleanup 
* Batch - Moving summary generation into ResultSet class, adding generation of ordinals for resultset and locking of result set list (which needs further refinement, but would be outside scope of this change)
* Adding new event and associated parameters for completion of a resultset. Params return the resultset summary
* Adding logic for assigning the event a handler in the query execution service
* Adding unit tests for testing the new event /making sure the existing tests work
* Refactoring some private properties into member variables

* Refactor to remove SectionData class in favor of BufferRange

* Adding callback for batch completion that will let the extension know that a batch has completed execution

* Refactoring to make progressive results work as per async query execution

* Allowing retrieval of batch results while query is in progress

* reverting global.json, whoops

* Adding a few missing comments, and fixing a couple code style bugs

* Using SelectionData everywhere again

* One more missing comment

* Adding new notification type for result set completion

* Plumbing event for result set completion

* Unit tests for result set events

This includes a fairly substantial change to create a mock of the
ConnectionService and to create separate memorystream storage arrays. It
preserves more correct behavior with a integration test, fixes an issue
where the test db reader will return n-1 rows because the Reliable
Connection Helper steals a record.

* Adding locking to ResultSets for thread safety

* Adding/fixing unit tests

* Adding batch ID to result set summary

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/QueryExecutionService.cs

@@ -437,7 +437,6 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                 };
                 await requestContext.SendEvent(QueryExecuteCompleteEvent.Type, eventParams);
             };
-
             query.QueryCompleted += callback;
             query.QueryFailed += callback;
             query.QueryConnectionException += errorCallback;
@@ -454,6 +453,18 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             };
             query.BatchCompleted += batchCallback;
 
+            // Setup the ResultSet completion callback
+            ResultSet.ResultSetAsyncEventHandler resultCallback = async r =>
+            {
+                QueryExecuteResultSetCompleteParams eventParams = new QueryExecuteResultSetCompleteParams
+                {
+                    ResultSetSummary = r.Summary,
+                    OwnerUri = executeParams.OwnerUri
+                };
+                await requestContext.SendEvent(QueryExecuteResultSetCompleteEvent.Type, eventParams);
+            };
+            query.ResultSetCompleted += resultCallback;
+
             // Launch this as an asynchronous task
             query.Execute();