Migrate /vip to Helix API (#4010)

Fixes #3983 

Co-authored-by: iProdigy <iProdigy@users.noreply.github.com>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/providers/twitch/api/Helix.hpp

@@ -381,6 +381,16 @@ enum class HelixRemoveChannelModeratorError {
     Forwarded,
 };
 
+enum class HelixAddChannelVIPError {
+    Unknown,
+    UserMissingScope,
+    UserNotAuthorized,
+    Ratelimited,
+
+    // The error message is forwarded directly from the Twitch API
+    Forwarded,
+};
+
 class IHelix
 {
 public:
@@ -536,6 +546,11 @@ public:
         FailureCallback<HelixSendChatAnnouncementError, QString>
             failureCallback) = 0;
 
+    // https://dev.twitch.tv/docs/api/reference#add-channel-vip
+    virtual void addChannelVIP(
+        QString broadcasterID, QString userID, ResultCallback<> successCallback,
+        FailureCallback<HelixAddChannelVIPError, QString> failureCallback) = 0;
+
     virtual void update(QString clientId, QString oauthToken) = 0;
 };
 
@@ -684,6 +699,12 @@ public:
         FailureCallback<HelixSendChatAnnouncementError, QString>
             failureCallback) final;
 
+    // https://dev.twitch.tv/docs/api/reference#add-channel-vip
+    void addChannelVIP(QString broadcasterID, QString userID,
+                       ResultCallback<> successCallback,
+                       FailureCallback<HelixAddChannelVIPError, QString>
+                           failureCallback) final;
+
     void update(QString clientId, QString oauthToken) final;
 
     static void initialize();