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/Exceptions.cs

@@ -0,0 +1,78 @@
+using System;
+using System.Security.Authentication;
+using Spectre.Console;
+
+namespace Generator.Commands.Samples
+{
+    public class Exceptions
+    {
+        internal abstract class BaseExceptionSample : BaseSample
+        {
+            public override (int Cols, int Rows) ConsoleSize => (base.ConsoleSize.Cols, 12);
+
+            protected readonly Exception Exception = null!;
+
+            protected BaseExceptionSample()
+            {
+                try
+                {
+                    DoMagic(42, null);
+                }
+                catch (Exception ex)
+                {
+                    Exception = ex;
+                }
+            }
+        }
+
+        internal class DefaultExceptionSample : BaseExceptionSample
+        {
+            public override void Run(IAnsiConsole console) => console.WriteException(Exception);
+        }
+
+        internal class ShortenedExceptionSample : BaseExceptionSample
+        {
+            public override void Run(IAnsiConsole console) => console.WriteException(Exception, ExceptionFormats.ShortenEverything | ExceptionFormats.ShowLinks);
+        }
+
+        internal class CustomColorsExceptionSample : BaseExceptionSample
+        {
+            public override void Run(IAnsiConsole console)
+            {
+                console.WriteException(Exception, new ExceptionSettings
+                {
+                    Format = ExceptionFormats.ShortenEverything | ExceptionFormats.ShowLinks,
+                    Style = new ExceptionStyle
+                    {
+                        Exception = new Style().Foreground(Color.Grey),
+                        Message = new Style().Foreground(Color.White),
+                        NonEmphasized = new Style().Foreground(Color.Cornsilk1),
+                        Parenthesis = new Style().Foreground(Color.Cornsilk1),
+                        Method = new Style().Foreground(Color.Red),
+                        ParameterName = new Style().Foreground(Color.Cornsilk1),
+                        ParameterType = new Style().Foreground(Color.Red),
+                        Path = new Style().Foreground(Color.Red),
+                        LineNumber = new Style().Foreground(Color.Cornsilk1),
+                    }
+                });
+            }
+        }
+
+        private static void DoMagic(int foo, string[,] bar)
+        {
+            try
+            {
+                CheckCredentials(foo, bar);
+            }
+            catch(Exception ex)
+            {
+                throw new InvalidOperationException("Whaaat?", ex);
+            }
+        }
+
+        private static void CheckCredentials(int qux, string[,] corgi)
+        {
+            throw new InvalidCredentialException("The credentials are invalid.");
+        }
+    }
+}