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

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

@@ -0,0 +1,16 @@
+#nullable disable
+namespace NadekoBot.Modules.Xp.Services;
+
+public class UserCacheItem
+{
+    public IGuildUser User { get; set; }
+    public IGuild Guild { get; set; }
+    public IMessageChannel Channel { get; set; }
+    public int XpAmount { get; set; }
+
+    public override int GetHashCode()
+        => User.GetHashCode();
+
+    public override bool Equals(object obj)
+        => obj is UserCacheItem uci && uci.User == User;
+}