DeFiCh/ain:1.7.x DeFi CustomTx (DfTx)

[fuxingloh]

Similar to #108

Implementation of 1.7.x Custom DfTx
https://github.com/DeFiCh/ain/blob/6428ac0ca470dd16f973d62b74a1ec0b9e5444a8/src/masternodes/mn_checks.h#L62-L67

enum class CustomTxType : uint8_t
{
  AppointOracle         = 'o',
  RemoveOracleAppoint   = 'h',
  UpdateOracleAppoint   = 't',
  SetOracleData         = 'y',
}

in

packages/jellyfish-transaction/src/script/defi/*

All CustomTX has a starting signature of DfTx in utf8 or 0x44665478. It is as it is, don't need to convert from BE to LE.

They are structured as a

1. VarUInt + [OP_RETURN + DfTx + TYPES[CxTxType] + ...]
2. VarUInt + 6a + 44665478 + Type + ...

Refer to #108 for a detailed implementation guide

[monstrobishi]

Will implement RemoveOracleAppoint as RemoveOracle and UpdateOracleAppoint as UpdateOracle to be in line with RPC calls and make more sense in general