Update Options dialog icons

A new set of scalable and themable icons with unified look as provided
by Diana.

Task-number: QTCREATORBUG-20325
Change-Id: I68498b034e9e43fbb61511a38d9c7fc0003ab076
Reviewed-by: hjk <hjk@qt.io>

src/plugins/cpptools/cppcodemodelsettingspage.cpp

@@ -165,7 +165,8 @@ CppCodeModelSettingsPage::CppCodeModelSettingsPage(QSharedPointer<CppCodeModelSe
     setDisplayName(QCoreApplication::translate("CppTools",Constants::CPP_CODE_MODEL_SETTINGS_NAME));
     setCategory(Constants::CPP_SETTINGS_CATEGORY);
     setDisplayCategory(QCoreApplication::translate("CppTools", "C++"));
-    setCategoryIcon(Utils::Icon(":/cpptools/images/category_cpp.png"));
+    setCategoryIcon(Utils::Icon({{":/cpptools/images/settingscategory_cpp.png",
+                    Utils::Theme::PanelTextColorDark}}, Utils::Icon::Tint));
 }
 
 QWidget *CppCodeModelSettingsPage::widget()

src/plugins/cpptools/cpptools.qrc

@@ -1,5 +1,6 @@
 <RCC>
     <qresource prefix="/cpptools">
-        <file>images/category_cpp.png</file>
+        <file>images/settingscategory_cpp.png</file>
+        <file>images/settingscategory_cpp@2x.png</file>
     </qresource>
 </RCC>