Add extension method to run workflows until end

src/modules/Elsa.Workflows.Core/Extensions/WorkflowRunnerExtensions.cs

@@ -0,0 +1,48 @@
+using Elsa.Workflows.Core.Contracts;
+using Elsa.Workflows.Core.Models;
+using Elsa.Workflows.Core.State;
+using JetBrains.Annotations;
+
+// ReSharper disable once CheckNamespace
+namespace Elsa.Extensions;
+
+/// <summary>
+/// Contains extension methods for <see cref="IWorkflowRunner"/>.
+/// </summary>
+[PublicAPI]
+public static class WorkflowRunnerExtensions
+{
+    /// <summary>
+    /// Runs a workflow until its end, automatically resuming any bookmark it encounters.
+    /// </summary>
+    public static async Task<WorkflowState> RunUntilEndAsync(
+        this IWorkflowRunner workflowRunner, 
+        IActivity activity,
+        Func<WorkflowState, Bookmark, RunWorkflowOptions, bool>? processBookmark = default,
+        CancellationToken cancellationToken = default)
+    {
+        var result = await workflowRunner.RunAsync(activity, cancellationToken: cancellationToken);
+        var workflow = result.Workflow;
+        var workflowState = result.WorkflowState;
+        var bookmarks = new Stack<Bookmark>(workflowState.Bookmarks);
+
+        // Continue resuming the workflow for as long as there are bookmarks to resume.
+        while (bookmarks.TryPop(out var bookmark))
+        {
+            var options = new RunWorkflowOptions(bookmarkId: bookmark.Id);
+            
+            // Give caller a chance to determine whether or not to resume the bookmark, as well as configure any input to provide.
+            if (processBookmark != null && !processBookmark(workflowState, bookmark, options))
+                continue;
+            
+            result = await workflowRunner.RunAsync(workflow, workflowState, options, cancellationToken: cancellationToken);
+            workflowState = result.WorkflowState;
+
+            foreach (var newBookmark in workflowState.Bookmarks)
+                bookmarks.Push(newBookmark);
+        }
+
+        // Return the workflow state.
+        return workflowState;
+    }
+}