Add support for fake input in asciicast recordings

* Fixes a bug with `SelectionPrompt` and page size.
* Allow `IAnsiConsoleInput` to return `null`.

resources/scripts/Generator/Commands/AsciiCast/Samples/ProgressSample.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using Spectre.Console;
+
+namespace Generator.Commands.Samples
+{
+    internal class ProgressSample : BaseSample
+    {
+        public override (int Cols, int Rows) ConsoleSize => (base.ConsoleSize.Cols, 10);
+
+        public override IEnumerable<(string Name, Action<Capabilities> CapabilitiesAction)> GetCapabilities()
+        {
+            yield return ("non-interactive", capabilities =>
+            {
+                capabilities.Ansi = false;
+                capabilities.Interactive = false;
+                capabilities.Legacy = false;
+                capabilities.Unicode = true;
+                capabilities.ColorSystem = ColorSystem.TrueColor;
+            });
+
+            foreach (var capability in base.GetCapabilities())
+            {
+                yield return capability;
+            }
+        }
+
+        public override void Run(IAnsiConsole console)
+        {
+            // Show progress
+            console.Progress()
+                .AutoClear(false)
+                .Columns(new TaskDescriptionColumn(), new ProgressBarColumn(), new PercentageColumn(), new RemainingTimeColumn(), new SpinnerColumn())
+                .Start(ctx =>
+                {
+                    var random = new Random(122978);
+
+                    // Create some tasks
+                    var tasks = CreateTasks(ctx, random);
+                    var warpTask = ctx.AddTask("Going to warp", autoStart: false).IsIndeterminate();
+
+                    // Wait for all tasks (except the indeterminate one) to complete
+                    while (!ctx.IsFinished)
+                    {
+                        // Increment progress
+                        foreach (var (task, increment) in tasks)
+                        {
+                            task.Increment(random.NextDouble() * increment);
+                        }
+
+                        // Simulate some delay
+                        Thread.Sleep(100);
+                    }
+
+                    // Now start the "warp" task
+                    warpTask.StartTask();
+                    warpTask.IsIndeterminate(false);
+                    while (!ctx.IsFinished)
+                    {
+                        warpTask.Increment(12 * random.NextDouble());
+
+                        // Simulate some delay
+                        Thread.Sleep(100);
+                    }
+                });
+        }
+
+        private static List<(ProgressTask Task, int Delay)> CreateTasks(ProgressContext progress, Random random)
+        {
+            var tasks = new List<(ProgressTask, int)>();
+
+            var names = new[]
+            {
+                "Retriculating algorithms", "Colliding splines", "Solving quarks", "Folding data structures",
+                "Rerouting capacitators "
+            };
+
+            for (var i = 0; i < 5; i++)
+            {
+                tasks.Add((progress.AddTask(names[i]), random.Next(2, 10)));
+            }
+
+            return tasks;
+        }
+    }
+}