DevTools: Use default constructors/destructors

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#cother-other-default-operation-rules

"The compiler is more likely to get the default semantics right and
you cannot implement these functions better than the compiler."

Userland/DevTools/Inspector/RemoteObjectGraphModel.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -22,10 +23,6 @@ RemoteObjectGraphModel::RemoteObjectGraphModel(RemoteProcess& process)
     m_timer_icon.set_bitmap_for_size(16, Gfx::Bitmap::try_load_from_file("/res/icons/16x16/timer.png").release_value_but_fixme_should_propagate_errors());
 }
 
-RemoteObjectGraphModel::~RemoteObjectGraphModel()
-{
-}
-
 GUI::ModelIndex RemoteObjectGraphModel::index(int row, int column, const GUI::ModelIndex& parent) const
 {
     if (!parent.is_valid()) {