No longer add username to the completion model in privateMessageReceived

The username is added to the completion model with the
"addRecentChatter" method instead

Moved "NameOptions" stuff from base class Channel to TwitchChannel where
it belongs

Remove unused Channel::getUsernamesForCompletions method

src/providers/twitch/twitchchannel.hpp

@@ -33,6 +33,8 @@ public:
     bool isBroadcaster();
     bool hasModRights();
 
+    void addRecentChatter(const std::shared_ptr<messages::Message> &message) final;
+
     const std::shared_ptr<chatterino::util::EmoteMap> bttvChannelEmotes;
     const std::shared_ptr<chatterino::util::EmoteMap> ffzChannelEmotes;
 
@@ -54,6 +56,11 @@ public:
     QString streamGame;
     QString streamUptime;
 
+    struct NameOptions {
+        QString displayName;
+        QString localizedName;
+    };
+
 private:
     explicit TwitchChannel(const QString &channelName, Communi::IrcConnection *readConnection);
 
@@ -71,6 +78,10 @@ private:
     Communi::IrcConnection *readConnecetion;
 
     friend class TwitchServer;
+
+    // Key = login name
+    std::map<QString, NameOptions> recentChatters;
+    std::mutex recentChattersMutex;
 };
 
 }  // namespace twitch