refactored the managers

src/singletons/completionmanager.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <QAbstractListModel>
+#include <QVector>
+#include <map>
+#include <string>
+
+#include "helper/completionmodel.hpp"
+
+namespace chatterino {
+class CompletionManager
+{
+    CompletionManager() = default;
+
+public:
+    static CompletionManager &getInstance();
+
+    CompletionModel *createModel(const std::string &channelName);
+
+private:
+    std::map<std::string, CompletionModel *> models;
+};
+
+}  // namespace chatterino