Themes: Make QPalette::Accent overridable by themes

QPalette::Accent was added in Qt 6, and missing in Qt Creator's support
for palette overriding. This change adds the respective theme roles and
lets the new themes set them with Token_Accent/_Subtle.

Change-Id: Ieefc8369b3f7050e5d96c1922ad753bcbbfd719e
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

share/qtcreator/themes/broccoli.tokenmapping

@@ -47,6 +47,8 @@ MenuItemTextColorNormal=Token_Text_Default
 MiniProjectTargetSelectorTextColor=Token_Text_Muted
 OutputPaneToggleButtonTextColorChecked=Token_Text_Muted
 OutputPaneToggleButtonTextColorUnchecked=Token_Text_Muted
+PaletteAccent=Token_Accent_Default
+PaletteAccentDisabled=Token_Accent_Subtle
 PaletteAlternateBase=Token_Background_Muted
 PaletteAlternateBaseDisabled=Token_Background_Subtle
 PaletteBase=Token_Background_Default

src/libs/utils/theme/theme.cpp

@@ -453,6 +453,8 @@ QPalette Theme::palette() const
         {PaletteShadowDisabled,            QPalette::Shadow,           QPalette::Disabled, false},
         {PalettePlaceholderText,           QPalette::PlaceholderText,  QPalette::All,      false},
         {PalettePlaceholderTextDisabled,   QPalette::PlaceholderText,  QPalette::Disabled, false},
+        {PaletteAccent,                    QPalette::Accent,           QPalette::All,      false},
+        {PaletteAccentDisabled,            QPalette::Accent,           QPalette::Disabled, false},
     };
 
     for (auto entry: mapping) {

src/libs/utils/theme/theme.h

@@ -128,6 +128,8 @@ public:
 
         PalettePlaceholderText,
         PalettePlaceholderTextDisabled,
+        PaletteAccent,
+        PaletteAccentDisabled,
 
         /* Icons */