feat: add early modrinth pack updating

Still some FIXMEs and TODOs to consider, but the general thing is here!

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/InstanceTask.h

@@ -43,10 +43,17 @@ public:
         return m_instGroup;
     }
 
+    bool shouldOverride() const { return m_override_existing; }
+
+protected:
+    void setOverride(bool override) { m_override_existing = override; }
+
 protected: /* data */
     SettingsObjectPtr m_globalSettings;
     QString m_instName;
     QString m_instIcon;
     QString m_instGroup;
     QString m_stagingPath;
+
+    bool m_override_existing = false;
 };