Expose txinwitness for coinbase in JSON form

txinwitness is used as the witness commitment nonce so is necessary if
reconstructing block data from RPC data.

src/core_write.cpp

@@ -198,6 +198,7 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
             o.pushKV("asm", ScriptToAsmStr(txin.scriptSig, true));
             o.pushKV("hex", HexStr(txin.scriptSig.begin(), txin.scriptSig.end()));
             in.pushKV("scriptSig", o);
+        }
         if (!tx.vin[i].scriptWitness.IsNull()) {
             UniValue txinwitness(UniValue::VARR);
             for (const auto& item : tx.vin[i].scriptWitness.stack) {
@@ -205,7 +206,6 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
             }
             in.pushKV("txinwitness", txinwitness);
         }
-        }
         in.pushKV("sequence", (int64_t)txin.nSequence);
         vin.push_back(in);
     }