Don't use .index for shaderpacks

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

launcher/minecraft/mod/ShaderPackFolderModel.cpp

@@ -0,0 +1,56 @@
+#include "ShaderPackFolderModel.h"
+
+namespace {
+class ShaderPackIndexMigrateTask : public Task {
+    Q_OBJECT
+   public:
+    ShaderPackIndexMigrateTask(QDir resourceDir, QDir indexDir) : m_resourceDir(std::move(resourceDir)), m_indexDir(std::move(indexDir)) {}
+
+    void executeTask() override
+    {
+        if (!m_indexDir.exists()) {
+            qDebug() << m_indexDir.absolutePath() << "does not exist; nothing to migrate";
+            emitSucceeded();
+            return;
+        }
+
+        QStringList pwFiles = m_indexDir.entryList({ "*.pw.toml" }, QDir::Files);
+        bool movedAll = true;
+
+        for (const auto& file : pwFiles) {
+            QString src = m_indexDir.filePath(file);
+            QString dest = m_resourceDir.filePath(file);
+
+            if (QFile::rename(src, dest)) {
+                qDebug() << "Moved" << src << "to" << dest;
+            } else {
+                movedAll = false;
+                qDebug() << "Error moving" << src << "to" << dest;
+            }
+        }
+
+        if (!movedAll) {
+            // FIXME: not shown in the UI
+            emitFailed(tr("Failed to migrate everything from .index"));
+            return;
+        }
+
+        if (!m_indexDir.removeRecursively()) {
+            emitFailed(tr("Failed to remove old .index dir"));
+            return;
+        }
+
+        emitSucceeded();
+    }
+
+   private:
+    QDir m_resourceDir, m_indexDir;
+};
+}  // namespace
+
+Task* ShaderPackFolderModel::createPreUpdateTask()
+{
+    return new ShaderPackIndexMigrateTask(m_dir, ResourceFolderModel::indexDir());
+}
+
+#include "ShaderPackFolderModel.moc"