feat(SvgButton): Allow custom color (#6268)

src/widgets/buttons/SvgButton.hpp

@@ -2,8 +2,11 @@
 
 #include "widgets/buttons/Button.hpp"
 
+#include <QColor>
 #include <QString>
 
+#include <optional>
+
 class QSvgRenderer;
 
 namespace chatterino {
@@ -41,6 +44,13 @@ public:
     /// Setter for #source()
     void setSource(Src source);
 
+    /// Sets a custom color to render over the SVG.
+    /// This allows you to change the color of a button to a solid color
+    /// of your choice without using multiple SVG resources.
+    ///
+    /// Set to std::nullopt to not override the color.
+    void setColor(std::optional<QColor> color);
+
     /// @brief Returns the padding inside the button.
     ///
     /// `width` is the padding applied horizontally (left and right).
@@ -65,6 +75,7 @@ private:
     Src source_;
     QSvgRenderer *svg_;
     QSize padding_;
+    std::optional<QColor> color_;
 };
 
 }  // namespace chatterino