Add custom image functionality for inline mod buttons. (#5369)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/helper/IconDelegate.hpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <QStyledItemDelegate>
+
+namespace chatterino {
+
+/**
+ * IconDelegate draws the decoration role pixmap scaled down to a square icon
+ */
+class IconDelegate : public QStyledItemDelegate
+{
+public:
+    explicit IconDelegate(QObject *parent = nullptr);
+
+    void paint(QPainter *painter, const QStyleOptionViewItem &option,
+               const QModelIndex &index) const override;
+};
+
+}  // namespace chatterino