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/help/generalsettingspage.cpp

@@ -55,7 +55,8 @@ GeneralSettingsPage::GeneralSettingsPage()
     setDisplayName(tr("General"));
     setCategory(Help::Constants::HELP_CATEGORY);
     setDisplayCategory(QCoreApplication::translate("Help", "Help"));
-    setCategoryIcon(Utils::Icon(":/help/images/category_help.png"));
+    setCategoryIcon(Utils::Icon({{":/help/images/settingscategory_help.png",
+                    Utils::Theme::PanelTextColorDark}}, Utils::Icon::Tint));
 }
 
 QWidget *GeneralSettingsPage::widget()

src/plugins/help/help.qrc

@@ -1,6 +1,7 @@
 <RCC>
     <qresource prefix="/help">
-        <file>images/category_help.png</file>
+        <file>images/settingscategory_help.png</file>
+        <file>images/settingscategory_help@2x.png</file>
         <file>images/mode_help.png</file>
         <file>images/mode_help@2x.png</file>
         <file>images/mode_help_mask.png</file>