Fix #127582: Crash when clicking onto particle settings button

This is due to memory allocation mismatch. `MEM_dupallocN` is used on
cpp style `ButsTextureUser` pointer. Now fixed by using `MEM_new`. Also
pass `uiButArgNFree/Copy` callback fn arguments to avoid the use of
default arguments which are C style.

Pull Request: https://projects.blender.org/blender/blender/pulls/127690

source/blender/editors/space_buttons/buttons_texture.cc

@@ -515,7 +515,12 @@ static void template_texture_user_menu(bContext *C, uiLayout *layout, void * /*a
                            0.0,
                            0.0,
                            "");
-    UI_but_funcN_set(but, template_texture_select, MEM_dupallocN(user), nullptr);
+    UI_but_funcN_set(but,
+                     template_texture_select,
+                     MEM_new<ButsTextureUser>("ButsTextureUser", *user),
+                     nullptr,
+                     but_func_argN_free<ButsTextureUser>,
+                     but_func_argN_copy<ButsTextureUser>);
 
     last_category = user->category;
   }