fix: Use built-in RNG (#1599)

### Summary

.NET 8 supports Xoroshiro 256** off the shelf and added Shuffle. Switching to that implementation.

### Developer Notes

* Removed many convenience methods that weren't used.

Projects/Server/Random/BuiltInRng.cs

@@ -0,0 +1,47 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright 2019-2023 - ModernUO Development Team                       *
+ * Email: [email protected]                                                *
+ * File: BuiltInRng.cs                                                   *
+ *                                                                       *
+ * This program is free software: you can redistribute it and/or modify  *
+ * it under the terms of the GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3 of the License, or     *
+ * (at your option) any later version.                                   *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace Server.Random;
+
+public static class BuiltInRng
+{
+    public static System.Random Generator { get; private set; } = new();
+
+    public static void Reset() => Generator = new System.Random();
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int Next() => Generator.Next();
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int Next(int maxValue) => Generator.Next(maxValue);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int Next(int minValue, int count) => minValue + Generator.Next(count);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static long Next(long maxValue) => Generator.NextInt64(maxValue);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static long Next(long minValue, long count) => minValue + Generator.NextInt64(count);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static double NextDouble() => Generator.NextDouble();
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void NextBytes(Span<byte> buffer) => Generator.NextBytes(buffer);
+}