refactor: move mod tasks to their own subfolder

Makes the launcher/minecraft/mod/ folder a little more organized.

launcher/minecraft/mod/tasks/ModFolderLoadTask.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <QDir>
+#include <QMap>
+#include <QObject>
+#include <QRunnable>
+#include <memory>
+#include "minecraft/mod/Mod.h"
+
+class ModFolderLoadTask : public QObject, public QRunnable
+{
+    Q_OBJECT
+public:
+    struct Result {
+        QMap<QString, Mod> mods;
+    };
+    using ResultPtr = std::shared_ptr<Result>;
+    ResultPtr result() const {
+        return m_result;
+    }
+
+public:
+    ModFolderLoadTask(QDir& mods_dir, QDir& index_dir);
+    void run();
+signals:
+    void succeeded();
+private:
+    QDir& m_mods_dir, m_index_dir;
+    ResultPtr m_result;
+};