fix: correctly override user color in sub gifts (#6322)

src/providers/twitch/UserColor.hpp

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "messages/MessageColor.hpp"
+
+#include <QString>
+
+#include <optional>
+
+class QColor;
+
+namespace chatterino {
+
+class IUserDataController;
+class ChannelChatters;
+
+namespace twitch {
+
+struct GetUserColorParams {
+    QString userLogin;
+    QString userID;
+
+    const IUserDataController *userDataController{};
+    const ChannelChatters *channelChatters{};
+
+    QColor color;
+};
+
+/// Attempt to get the color of the user based on the provided parameters.
+///
+/// If there's a valid color for the given user ID in the user data controller, return it.
+/// If there's a valid `color` parameter, return it.
+/// If there's a valid color for the given user login in the channel chatters set, return it.
+/// Otherwise, return nullopt.
+std::optional<MessageColor> getUserColor(const GetUserColorParams &params);
+
+}  // namespace twitch
+}  // namespace chatterino