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/BarChartSample.cs

@@ -0,0 +1,20 @@
+using Spectre.Console;
+
+namespace Generator.Commands.Samples
+{
+    internal class BarChartSample : BaseSample
+    {
+        public override (int Cols, int Rows) ConsoleSize => (base.ConsoleSize.Cols, 5);
+
+        public override void Run(IAnsiConsole console)
+        {
+            console.Write(new BarChart()
+                .Width(60)
+                .Label("[green bold underline]Number of fruits[/]")
+                .CenterLabel()
+                .AddItem("Apple", 12, Color.Yellow)
+                .AddItem("Orange", 54, Color.Green)
+                .AddItem("Banana", 33, Color.Red));
+        }
+    }
+}