Create utility RPCs for PSBT

decodepsbt takes a PSBT and decodes it to JSON

combinepsbt takes multiple PSBTs for the same tx and combines them.

finalizepsbt takes a PSBT and finalizes the inputs. If all inputs
are final, it extracts the network serialized transaction and returns
that instead of a PSBT unless instructed otherwise.

createpsbt is like createrawtransaction but for PSBTs instead of
raw transactions.

convertpsbt takes a network serialized transaction and converts it
into a psbt. The resulting psbt will lose all signature data and
an explicit flag must be set to allow transactions with signature
data to be converted.

src/core_io.h

@@ -14,6 +14,7 @@ class CBlock;
 class CScript;
 class CTransaction;
 struct CMutableTransaction;
+struct PartiallySignedTransaction;
 class uint256;
 class UniValue;
 
@@ -24,12 +25,15 @@ bool DecodeHexTx(CMutableTransaction& tx, const std::string& hex_tx, bool try_no
 bool DecodeHexBlk(CBlock&, const std::string& strHexBlk);
 uint256 ParseHashStr(const std::string&, const std::string& strName);
 std::vector<unsigned char> ParseHexUV(const UniValue& v, const std::string& strName);
+bool DecodePSBT(PartiallySignedTransaction& psbt, const std::string& base64_tx, std::string& error);
 
 // core_write.cpp
 UniValue ValueFromAmount(const CAmount& amount);
 std::string FormatScript(const CScript& script);
 std::string EncodeHexTx(const CTransaction& tx, const int serializeFlags = 0);
+std::string SighashToStr(unsigned char sighash_type);
 void ScriptPubKeyToUniv(const CScript& scriptPubKey, UniValue& out, bool fIncludeHex);
+void ScriptToUniv(const CScript& script, UniValue& out, bool include_address);
 void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry, bool include_hex = true, int serialize_flags = 0);
 
 #endif // BITCOIN_CORE_IO_H