refactor: move normalization to new function

Move the univalue formatting logic out of AddOutputs and into its own function,
`NormalizeOutputs`. This allows us to re-use this logic in later commits.

src/rpc/rawtransaction_util.cpp

@@ -70,7 +70,7 @@ void AddInputs(CMutableTransaction& rawTx, const UniValue& inputs_in, std::optio
     }
 }
 
-void AddOutputs(CMutableTransaction& rawTx, const UniValue& outputs_in)
+UniValue NormalizeOutputs(const UniValue& outputs_in)
 {
     if (outputs_in.isNull()) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, output argument must be non-null");
@@ -94,6 +94,13 @@ void AddOutputs(CMutableTransaction& rawTx, const UniValue& outputs_in)
         }
         outputs = std::move(outputs_dict);
     }
+    return outputs;
+}
+
+void AddOutputs(CMutableTransaction& rawTx, const UniValue& outputs_in)
+{
+    UniValue outputs(UniValue::VOBJ);
+    outputs = NormalizeOutputs(outputs_in);
 
     // Duplicate checking
     std::set<CTxDestination> destinations;

src/rpc/rawtransaction_util.h

@@ -42,7 +42,10 @@ void ParsePrevouts(const UniValue& prevTxsUnival, FillableSigningProvider* keyst
 /** Normalize univalue-represented inputs and add them to the transaction */
 void AddInputs(CMutableTransaction& rawTx, const UniValue& inputs_in, bool rbf);
 
-/** Normalize univalue-represented outputs and add them to the transaction */
+/** Normalize univalue-represented outputs */
+UniValue NormalizeOutputs(const UniValue& outputs_in);
+
+/** Normalize, parse, and add outputs to the transaction */
 void AddOutputs(CMutableTransaction& rawTx, const UniValue& outputs_in);
 
 /** Create a transaction from univalue parameters */