perf(strings): establish Utf8ToAsciiConverter baseline benchmarks

tests/Umbraco.Tests.Benchmarks/BenchmarkTextGenerator.cs

@@ -0,0 +1,63 @@
+using System.Text;
+
+namespace Umbraco.Tests.Benchmarks;
+
+public static class BenchmarkTextGenerator
+{
+    private const int Seed = 42;
+
+    private static readonly char[] AsciiAlphaNum =
+        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".ToCharArray();
+
+    private static readonly char[] AsciiPunctuation =
+        " .,;:!?-_'\"()".ToCharArray();
+
+    private static readonly char[] LatinAccented =
+        "àáâãäåæèéêëìíîïñòóôõöøùúûüýÿÀÁÂÃÄÅÆÈÉÊËÌÍÎÏÑÒÓÔÕÖØÙÚÛÜÝŸœŒßðÐþÞ".ToCharArray();
+
+    private static readonly char[] Cyrillic =
+        "АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдеёжзийклмнопрстуфхцчшщъыьэюя".ToCharArray();
+
+    private static readonly char[] Symbols =
+        "©®™€£¥°±×÷§¶†‡•".ToCharArray();
+
+    private static readonly char[] WorstCaseCyrillic =
+        "ЩЮЯЖЧШщюяжчш".ToCharArray();
+
+    public static string GeneratePureAscii(int length) =>
+        GenerateFromCharset(length, AsciiAlphaNum);
+
+    public static string GenerateMixed(int length)
+    {
+        var random = new Random(Seed);
+        var sb = new StringBuilder(length);
+
+        for (int i = 0; i < length; i++)
+        {
+            var roll = random.Next(100);
+            var charset = roll switch
+            {
+                < 70 => AsciiAlphaNum,
+                < 85 => AsciiPunctuation,
+                < 95 => LatinAccented,
+                < 99 => Cyrillic,
+                _ => Symbols
+            };
+            sb.Append(charset[random.Next(charset.Length)]);
+        }
+
+        return sb.ToString();
+    }
+
+    public static string GenerateWorstCase(int length) =>
+        GenerateFromCharset(length, WorstCaseCyrillic);
+
+    private static string GenerateFromCharset(int length, char[] charset)
+    {
+        var random = new Random(Seed);
+        var sb = new StringBuilder(length);
+        for (int i = 0; i < length; i++)
+            sb.Append(charset[random.Next(charset.Length)]);
+        return sb.ToString();
+    }
+}