message: Add global_xpubs to decodepsbt
diff: // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  +#include <base58.h>
  #include <chain.h>
  #include <coins.h>
  #include <consensus/amount.h>
  @@ -1049,6 +1050,15 @@ static RPCHelpMan decodepsbt()
  {
  {RPCResult::Type::ELISION, "", "The layout is the same as the output of decoderawtransaction."},
  }},
  + {RPCResult::Type::ARR, "global_xpubs", "",
  + {
  + {RPCResult::Type::OBJ, "", "",
  + {
  + {RPCResult::Type::STR, "xpub", "The extended public key this path corresponds to"},
  + {RPCResult::Type::STR_HEX, "master_fingerprint", "The fingerprint of the master key"},
  + {RPCResult::Type::STR, "path", "The path"},
  + }},
  + }},
  {RPCResult::Type::NUM, "psbt_version", "The PSBT version number. Not to be confused with the unsigned transaction version"},
  {RPCResult::Type::ARR, "proprietary", "The global proprietary map",
  {
  @@ -1199,6 +1209,23 @@ static RPCHelpMan decodepsbt()
  TxToUniv(CTransaction(*psbtx.tx), uint256(), tx_univ, false);
  result.pushKV("tx", tx_univ);
  + // Add the global xpubs
  + UniValue global_xpubs(UniValue::VARR);
  + for (std::pair<KeyOriginInfo, std::set<CExtPubKey>> xpub_pair : psbtx.m_xpubs) {
  + for (auto& xpub : xpub_pair.second) {
  + std::vector<unsigned char> ser_xpub;
  + ser_xpub.assign(BIP32_EXTKEY_WITH_VERSION_SIZE, 0);
  + xpub.EncodeWithVersion(ser_xpub.data());
  +
  + UniValue keypath(UniValue::VOBJ);
  + keypath.pushKV("xpub", EncodeBase58Check(ser_xpub));
  + keypath.pushKV("master_fingerprint", HexStr(Span<unsigned char>(xpub_pair.first.fingerprint, xpub_pair.first.fingerprint + 4)));
  + keypath.pushKV("path", WriteHDKeypath(xpub_pair.first.path));
  + global_xpubs.push_back(keypath);
  + }
  + }
  + result.pushKV("global_xpubs", global_xpubs);
  +
  // PSBT version
  result.pushKV("psbt_version", static_cast<uint64_t>(psbtx.GetVersion()));
  