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

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

@@ -0,0 +1,29 @@
+#nullable disable
+using NadekoBot.Modules.Xp.Services;
+using NadekoBot.Services.Database.Models;
+
+namespace NadekoBot.Modules.Xp.Extensions;
+
+public static class Extensions
+{
+    public static (int Level, int LevelXp, int LevelRequiredXp) GetLevelData(this UserXpStats stats)
+    {
+        var 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 > stats.Xp)
+                break;
+
+            totalXp += required;
+            lvl++;
+        }
+
+        return (lvl - 1, stats.Xp - totalXp, required);
+    }
+}