Add ability to create sessions from templates, and list existing sessions (#671)

* Initial changes to connect to existing sessions

* Creating new profiler sessions

* Some session template changes

* Fixing errors

* Cleaning up comments, string constants, and formatting

* Removing commented code

test/Microsoft.SqlTools.ServiceLayer.UnitTests/Profiler/ProfilerServiceTests.cs

@@ -40,7 +40,6 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.Profiler
                 .Returns<StartProfilingResult>((result) =>
                 {
                     // capture the session id for sending the stop message
-                    sessionId = result.SessionId;
                     return Task.FromResult(0);
                 });
 
@@ -60,7 +59,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.Profiler
 
             var requestParams = new StartProfilingParams();
             requestParams.OwnerUri = testUri;
-            requestParams.TemplateName = "Standard";
+            requestParams.SessionName = "Standard";
 
             // start profiling session
             await profilerService.HandleStartProfilingRequest(requestParams, requestContext.Object);