Feature execution plan settings and request implementation (#213)

* experimental showplan implementation (tools side only)

* fix for redundant massages from showplan executions

* moved showplan batches to new variables to make it less confusing

* returns showplan as part of batch summary with in each result summary

* cleaned up showplan resultsets

* cleaning up code and making showplan var optional

* changes all var names to showplan

* adding estimated support

* small fixes

* updatin var names and adding EPOptions struct

* adding ssms execution plan logic based on server types

* adding special actions logic

* removing redundant name changes

* execution plan query handler added

* cleaning up functions and data structures

* seperated special actions into its own class

* cleaning up special actions

* cleaning up code

* small new line fixes

* commenting out pre-yukon code

* removing all pre yukon code

* last yukon code commented out

* fixes broken tests

* adding related unit tests; integration tests incoming

* finishing tests and cleaning up code

* semantic changes

* cleaning up semantics

* changes and test fixes, also adding new exceptions into RS

* fixing special actions and cleaning up request logic

* fixing comment to trigger new build

* triggering another  build

* fixed up specialaction and added tests for it

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/ResultSetSummary.cs

@@ -29,5 +29,11 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
         /// Details about the columns that are provided as solutions
         /// </summary>
         public DbColumnWrapper[] ColumnInfo { get; set; }
+
+        /// <summary>
+        /// The special action definition of the result set 
+        /// </summary>
+        public SpecialAction SpecialAction { get; set; }
+
     }
 }