Adds a execute and return result message (#383)

* inital request

* refactored query execution failure callback to take exception

* added failure callback to execute and return

* added test for query execute and return

* updated params

* removed dead code

* addressed feedback; added multiple active result set support; updated tests

* addessed feedback and added testing and errors and verification

* change <= to ==

* changed name of trashQ to removedQuery

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/ExecuteRequests/SimpleExecuteRequest.cs

@@ -0,0 +1,54 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts.ExecuteRequests
+{
+    /// <summary>
+    /// Parameters for executing a query from a provided string
+    /// </summary>
+    public class SimpleExecuteParams
+    {
+        /// <summary>
+        /// The string to execute
+        /// </summary>
+        public string QueryString { get; set; }
+
+        /// <summary>
+        /// The owneruri to get connection from
+        /// </summary>
+        public string OwnerUri { get; set; }
+    }
+
+    /// <summary>
+    /// Result
+    /// </summary>
+    public class SimpleExecuteResult
+    {
+
+        /// <summary>
+        /// The number of rows that was returned with the resultset
+        /// </summary>
+        public long RowCount { get; set; }
+
+        /// <summary>
+        /// Details about the columns that are provided as solutions
+        /// </summary>
+        public DbColumnWrapper[] ColumnInfo { get; set; }
+
+        /// <summary>
+        /// 2D array of the cell values requested from result set
+        /// </summary>
+        public DbCellValue[][] Rows { get; set; }
+    }
+
+    public class SimpleExecuteRequest
+    {
+        public static readonly
+            RequestType<SimpleExecuteParams, SimpleExecuteResult> Type =
+            RequestType<SimpleExecuteParams, SimpleExecuteResult>.Create("query/simpleexecute");
+    }
+}