Remove borders and paddings from native controls on Linux (#14873)

* init

* update

* Update SpinInput.cpp

* possible fix for em_unit

* button alignment

* match titlebar height

* revert em_value for macOS and Windows

* Update GUI_Utils.hpp

* Merge branch 'main' into linux-black-borders-2

* Revert "button alignment"

This reverts commit 3fc7461071.

* Revert "match titlebar height"

This reverts commit c4aa1d9f1e.

* revert dpi changes

* match platform tags

* remove radio box borders

* Fix code indent

src/slic3r/GUI/Widgets/SwitchButton.cpp

@@ -12,7 +12,7 @@
 #include "libslic3r/MacUtils.hpp"
 #endif
 
-#ifdef __WXGTK3__
+#ifdef __WXGTK__
 #include "../GUI_Utils.hpp"
 #endif
 
@@ -37,7 +37,7 @@ SwitchButton::SwitchButton(wxWindow* parent, wxWindowID id)
 	Bind(wxEVT_TOGGLEBUTTON, [this](auto& e) { update(); e.Skip(); });
 	SetFont(Label::Body_12);
 
-#ifdef __WXGTK3__
+#ifdef __WXGTK__
     Slic3r::GUI::RemoveButtonBorder(this);
 #endif