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

test/Microsoft.SqlTools.ServiceLayer.Test/QueryExecution/Common.cs

@@ -32,7 +32,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.QueryExecution
 
         public const string NoOpQuery = "-- No ops here, just us chickens.";
 
-        public const int Ordinal = 0;
+        public const int Ordinal = 100;     // We'll pick something other than default(int)
 
         public const string OwnerUri = "testFile";
 
@@ -161,7 +161,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.QueryExecution
             var connectionMock = new Mock<DbConnection> { CallBase = true };
             connectionMock.Protected()
                 .Setup<DbCommand>("CreateDbCommand")
-                .Returns(CreateTestCommand(data, throwOnRead));
+                .Returns(() => CreateTestCommand(data, throwOnRead));
             connectionMock.Setup(dbc => dbc.Open())
                 .Callback(() => connectionMock.SetupGet(dbc => dbc.State).Returns(ConnectionState.Open));
             connectionMock.Setup(dbc => dbc.Close())
@@ -174,7 +174,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.QueryExecution
         {
             var mockFactory = new Mock<ISqlConnectionFactory>();
             mockFactory.Setup(factory => factory.CreateSqlConnection(It.IsAny<string>()))
-                .Returns(CreateTestConnection(data, throwOnRead));
+                .Returns(() => CreateTestConnection(data, throwOnRead));
 
             return mockFactory.Object;
         }