getrawtransaction: inform about blockhash argument when lookup fails
Summary: This is a backport of Core PR16217
Test Plan:
$ src/bitcoin-cli getrawtransaction 1df224c31dbfbfcefe3d3de6671e53e73d6cd123628d491db9db3f1558f3110a error code: -5 error message: No such mempool transaction. Use -txindex or provide a block hash to enable blockchain transaction queries. Use gettransaction for wallet transactions.
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D8366