Make save result async (#107)

* Make save results asynchronous

* Prevent write share of file

* Lock objects in stages

* Create Save result objects

* refactor and write rows in batches

* CHange batchSize from test value

* Remove await in handler

* Removing the file reader as a member of the resultset

* Change Dispose to wait for save

* Change concurrentBag

* PascalCase variables

* Modify function signature and tests

* Safe file methods

* refactor ResultSets to Ilist and remove ToList

* Change dictionary key and prevent add to saveTasks during dispose

* Simplify row concatenation

* Fix prevent add

* Fix prevent add

* Add methods to expose saveTasks and isBeingDisposed

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

@@ -60,17 +60,6 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
     /// Parameters to save results as CSV
     /// </summary>
     public class SaveResultsAsCsvRequestParams: SaveResultsRequestParams{
-        
-        /// <summary>
-        /// CSV - Write values in quotes 
-        /// </summary>
-        public Boolean ValueInQuotes { get; set; }
-
-        /// <summary>
-        /// The encoding of the file to save results in
-        /// </summary>
-        public string FileEncoding { get; set; }
-
         /// <summary>
         /// Include headers of columns in CSV
         /// </summary>