Add DAP server (#4298)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Tingluo Huang <tingluohuang@github.com>

src/Runner.Worker/StepsRunner.cs

@@ -10,6 +10,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Runner.Worker.Expressions;
 
 namespace GitHub.Runner.Worker
@@ -50,6 +51,7 @@ namespace GitHub.Runner.Worker
             jobContext.JobContext.Status = (jobContext.Result ?? TaskResult.Succeeded).ToActionResult();
             var scopeInputs = new Dictionary<string, PipelineContextData>(StringComparer.OrdinalIgnoreCase);
             bool checkPostJobActions = false;
+            var dapDebugger = HostContext.GetService<IDapDebugger>();
             while (jobContext.JobSteps.Count > 0 || !checkPostJobActions)
             {
                 if (jobContext.JobSteps.Count == 0 && !checkPostJobActions)
@@ -226,9 +228,14 @@ namespace GitHub.Runner.Worker
                         }
                         else
                         {
+                            // Pause for DAP debugger before step execution
+                            await dapDebugger?.OnStepStartingAsync(step);
+
                             // Run the step
                             await RunStepAsync(step, jobContext.CancellationToken);
                             CompleteStep(step);
+
+                            dapDebugger?.OnStepCompleted(step);
                         }
                     }
                     finally
@@ -255,6 +262,7 @@ namespace GitHub.Runner.Worker
 
                 Trace.Info($"Current state: job state = '{jobContext.Result}'");
             }
+
         }
 
         private async Task RunStepAsync(IStep step, CancellationToken jobCancellationToken)