[Icons] Keep semantic red and green on themed glyphs

The one-glyph cutover recolored every icon from a single palette role, so a
disabled deck, a not-ready player and a remove button all lost the red or green
that carried their meaning.

Add Positive and Negative application colors beside the accents, ship
scheme-appropriate defaults for every theme, and resolve them through
ThemeManager. Icons now take an IconTint: a palette role for structural glyphs,
or a semantic role for states and add/remove actions. A disabled semantic icon
falls back to the disabled foreground; on a selected row a semantic tint keeps
its color only while it stays legible on the highlight, and a palette tint keeps
the existing WindowText -> HighlightedText swap.

cockatrice/src/interface/theme_config.cpp

@@ -9,6 +9,7 @@
 #include <QList>
 #include <QMetaEnum>
 #include <QPair>
+#include <QStringLiteral>
 #include <QTextStream>
 #include <qnamespace.h>
 #include <utility>
@@ -451,3 +452,19 @@ FontConfig FontConfig::fromThemeDir(const QString &themeDirPath)
 
     return fromFile(QDir(themeDirPath).absoluteFilePath(fileName()));
 }
+
+QColor defaultAppColor(AppColor::Role role, bool dark)
+{
+    switch (role) {
+        case AppColor::AccentStrong:
+        case AppColor::AccentSoft:
+            // Derived from the palette highlight by ThemeManager::appColor().
+            return {};
+        case AppColor::Positive:
+            return QColor(dark ? QStringLiteral("#6dd58c") : QStringLiteral("#1b7f3b"));
+        case AppColor::Negative:
+            return QColor(dark ? QStringLiteral("#ff8a80") : QStringLiteral("#b3261e"));
+    }
+
+    return {};
+}