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/BaseSample.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Spectre.Console;
+
+namespace Generator.Commands.Samples
+{
+    public abstract class BaseSample
+    {
+        public abstract void Run(IAnsiConsole console);
+        public virtual string Name() => PascalToKebab(GetType().Name.Replace("Sample",""));
+        public virtual (int Cols, int Rows) ConsoleSize => (82, 24);
+        public virtual IEnumerable<(string Name, Action<Capabilities> CapabilitiesAction)> GetCapabilities()
+        {
+            return new (string Name, Action<Capabilities> CapabilitiesAction)[]
+            {
+                ("plain", capabilities =>
+                {
+                    capabilities.Unicode = false;
+                    capabilities.Ansi = true;
+                    capabilities.Interactive = true;
+                    capabilities.Legacy = false;
+                    capabilities.Links = false;
+                    capabilities.ColorSystem = ColorSystem.Legacy;
+                }),
+                ("rich", capabilities =>
+                {
+                    capabilities.Unicode = true;
+                    capabilities.Ansi = true;
+                    capabilities.Interactive = true;
+                    capabilities.Legacy = false;
+                    capabilities.Links = false;
+                    capabilities.ColorSystem = ColorSystem.TrueColor;
+                }),
+            };
+        }
+
+        private string PascalToKebab(ReadOnlySpan<char> input)
+        {
+            var sb = new StringBuilder();
+            var previousUpper = true;
+            foreach (var chr in input)
+            {
+                if (char.IsUpper(chr) && previousUpper == false)
+                {
+                    sb.Append('-');
+                    previousUpper = true;
+                }
+                else
+                {
+                    previousUpper = false;
+                }
+
+                sb.Append(char.ToLower(chr));
+            }
+
+            return sb.ToString();
+
+        }
+    }
+}