refactor: move things around so that related things are close together

This also adds some comments around ModModel.cpp and ModPage.cpp to add
some ease of reading the code.

Also move some things from headers to cpp files.

launcher/ui/pages/modplatform/flame/FlameModModel.cpp

@@ -1,7 +1,24 @@
 #include "FlameModModel.h"
 
+#include "modplatform/flame/FlameModIndex.h"
+
 namespace FlameMod {
 
 const char* ListModel::sorts[6]{ "Featured", "Popularity", "LastUpdated", "Name", "Author", "TotalDownloads" };
 
+void ListModel::loadIndexedPack(ModPlatform::IndexedPack& m, QJsonObject& obj)
+{
+    FlameMod::loadIndexedPack(m, obj);
+};
+
+void ListModel::loadIndexedPackVersions(ModPlatform::IndexedPack& m, QJsonArray& arr)
+{
+    FlameMod::loadIndexedPackVersions(m, arr, APPLICATION->network(), m_parent->m_instance);
+};
+
+QJsonArray ListModel::documentToArray(QJsonDocument& obj) const
+{
+    return obj.array();
+}
+
 }  // namespace FlameMod