Fixed some crashes in response strings source generator, reorganized more submodules into their folders

src/NadekoBot/Modules/Xp/_Common/LevelStats.cs

@@ -0,0 +1,40 @@
+#nullable disable
+using NadekoBot.Modules.Xp.Services;
+
+namespace NadekoBot.Modules.Xp;
+
+public class LevelStats
+{
+    public int Level { get; }
+    public int LevelXp { get; }
+    public int RequiredXp { get; }
+    public int TotalXp { get; }
+
+    public LevelStats(int xp)
+    {
+        if (xp < 0)
+            xp = 0;
+
+        TotalXp = xp;
+
+        const int baseXp = XpService.XP_REQUIRED_LVL_1;
+
+        var required = baseXp;
+        var totalXp = 0;
+        var lvl = 1;
+        while (true)
+        {
+            required = (int)(baseXp + (baseXp / 4.0 * (lvl - 1)));
+
+            if (required + totalXp > xp)
+                break;
+
+            totalXp += required;
+            lvl++;
+        }
+
+        Level = lvl - 1;
+        LevelXp = xp - totalXp;
+        RequiredXp = required;
+    }
+}