Use ParamsWrapper for witness serialization

src/interfaces/chain.h

@@ -335,7 +335,7 @@ public:
     virtual void rpcRunLater(const std::string& name, std::function<void()> fn, int64_t seconds) = 0;
 
     //! Current RPC serialization flags.
-    virtual int rpcSerializationFlags() = 0;
+    virtual bool rpcSerializationWithoutWitness() = 0;
 
     //! Get settings value.
     virtual common::SettingsValue getSetting(const std::string& arg) = 0;