feat: support global tx in api.listTransactions and api.getTransaction (#1694)

feat: support global tx in api.listTransactions and api.getTransaction (#1694)

* feat: add wallet.SaveGlobalTxIdxFlag

* feat: add 	blockHash, position, err := parseGlobalTxIdx(string(globalTxIdx))

* feat: implement parseGlobalTxIdx

* wip

* fix: fix calcGlobalTxIndex()

* feat: support getGlobalTxByTxID() in GetTransactionByTxID()

* refactor: rename save_global_tx_index

* refactor: use encoding/binary for position in txIndex

* feat: use wallet.TxIndexFlag to control GetTransactionByTxID flow

* refactor: wrap txIndexFlag inside NewWallet()

* fix: fix wallet_test_util

* refactor: reduce globalTxIdx space by using bytes directly