refactor: move NetJob away from ModModel to ModAPI

This is done so that 1. ModAPI behaves more like an actual API instead
of just a helper, and 2. Allows for more easily creating other mod
providers that may or may not use network tasks (foreshadowing lol)

launcher/ui/pages/modplatform/ModPage.h

@@ -37,7 +37,7 @@ class ModPage : public QWidget, public BasePage {
     virtual bool shouldDisplay() const override = 0;
     const ModAPI* apiProvider() const { return api.get(); };
 
-    virtual void onRequestVersionsSucceeded(ModPage*, QByteArray*, QString) = 0;
+    virtual void onRequestVersionsSucceeded(QJsonDocument&, QString) = 0;
 
     void openedImpl() override;
     bool eventFilter(QObject* watched, QEvent* event) override;