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/AsciiCastExtensions.cs

@@ -0,0 +1,15 @@
+using Spectre.Console;
+
+namespace Generator.Commands
+{
+    public static class AsciiCastExtensions
+    {
+        public static AsciiCastOut WrapWithAsciiCastRecorder(this IAnsiConsole ansiConsole)
+        {
+            AsciiCastOut castRecorder = new(ansiConsole.Profile.Out);
+            ansiConsole.Profile.Out = castRecorder;
+
+            return castRecorder;
+        }
+    }
+}