refactor: Use a single indexed pack for mods

Since there's little difference between them, let's remove duplication
and merge them.

launcher/modplatform/ModIndex.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <QList>
+#include <QMetaType>
+#include <QString>
+#include <QVariant>
+#include <QVector>
+
+namespace ModPlatform {
+
+struct ModpackAuthor {
+    QString name;
+    QString url;
+};
+
+struct IndexedVersion {
+    QVariant addonId;
+    QVariant fileId;
+    QString version;
+    QVector<QString> mcVersion;
+    QString downloadUrl;
+    QString date;
+    QString fileName;
+    QVector<QString> loaders = {};
+};
+
+struct IndexedPack {
+    QVariant addonId;
+    QString name;
+    QString description;
+    QList<ModpackAuthor> authors;
+    QString logoName;
+    QString logoUrl;
+    QString websiteUrl;
+
+    bool versionsLoaded = false;
+    QVector<IndexedVersion> versions;
+};
+
+}  // namespace ModPlatform
+
+Q_DECLARE_METATYPE(ModPlatform::IndexedPack)