Add build statistics to TC engine

Author: agc93

src/Cake.TeamCity.Module/TeamCityEngine.cs

@@ -35,6 +35,9 @@ private void OnTaskTeardown(object sender, TaskTeardownEventArgs e)
             if (b.IsRunningOnTeamCity)
             {
                 var tc = b.TeamCity;
+                var duration = e.TaskTeardownContext.Duration.TotalMilliseconds.ToString("0");
+                // we really should add build statistic values to the TeamCity stuff in Cake, but this will do for now.
+                e.TaskTeardownContext.Log.Information($"##teamcity[buildStatisticValue key='Block.{e.TaskTeardownContext.Task.Name}.Duration' value='{duration}']");
                 tc.WriteEndProgress($"Completed running {e.TaskTeardownContext.Task.Name} task");
                 tc.WriteEndBlock(e.TaskTeardownContext.Task.Name);
             }