feat: add very early mod.toml packwiz support

Also use it as a on-disk format for storing mod metadata. This will be
used later on to make better mod managment.

launcher/minecraft/mod/LocalModUpdateTask.cpp

@@ -0,0 +1,32 @@
+#include "LocalModUpdateTask.h"
+
+#include <toml.h>
+
+#include "FileSystem.h"
+#include "modplatform/packwiz/Packwiz.h"
+
+LocalModUpdateTask::LocalModUpdateTask(QDir mods_dir, ModPlatform::IndexedPack& mod, ModPlatform::IndexedVersion& mod_version)
+    : m_mod(mod), m_mod_version(mod_version)
+{
+    // Ensure a '.index' folder exists in the mods folder, and create it if it does not
+    m_index_dir = { QString("%1/.index").arg(mods_dir.absolutePath()) };
+    if (!FS::ensureFolderPathExists(m_index_dir.path())) {
+        emitFailed(QString("Unable to create index for mod %1!").arg(m_mod.name));
+    }
+}
+
+void LocalModUpdateTask::executeTask()
+{
+    setStatus(tr("Updating index for mod:\n%1").arg(m_mod.name));
+
+    auto pw_mod = Packwiz::createModFormat(m_index_dir, m_mod, m_mod_version);
+    Packwiz::updateModIndex(m_index_dir, pw_mod);
+
+    emitSucceeded();
+}
+
+bool LocalModUpdateTask::abort()
+{
+    emitAborted();
+    return true;
+}

launcher/minecraft/mod/LocalModUpdateTask.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <QDir>
+
+#include "tasks/Task.h"
+#include "modplatform/ModIndex.h"
+
+class LocalModUpdateTask : public Task {
+    Q_OBJECT
+   public:
+    using Ptr = shared_qobject_ptr<LocalModUpdateTask>;
+
+    explicit LocalModUpdateTask(QDir mods_dir, ModPlatform::IndexedPack& mod, ModPlatform::IndexedVersion& mod_version);
+
+    bool canAbort() const override { return true; }
+    bool abort() override;
+
+   protected slots:
+    //! Entry point for tasks.
+    void executeTask() override;
+
+   private:
+    QDir m_index_dir;
+    ModPlatform::IndexedPack& m_mod;
+    ModPlatform::IndexedVersion& m_mod_version;
+};