CActor: Make Render() a non-const function

A few implementations of Render() contain const-casts nested within its
their call hierarchy to get around the fact that this function is marked
const. We can just make the member function non-const to allow removal
of these casts in follow up changes.

Runtime/World/CScriptAiJumpPoint.hpp

@@ -30,7 +30,7 @@ public:
   void Think(float, CStateManager&) override;
   void AcceptScriptMsg(EScriptObjectMessage, TUniqueId, CStateManager&) override;
   void AddToRenderer(const zeus::CFrustum&, CStateManager&) override {}
-  void Render(const CStateManager&) const override {}
+  void Render(CStateManager&) override {}
   std::optional<zeus::CAABox> GetTouchBounds() const override;
   bool GetInUse(TUniqueId uid) const;
   TUniqueId GetJumpPoint() const { return x10c_currentWaypoint; }