Update bitcoin-tx to use replay protected signatures

Summary: As per title.

Test Plan: bitcoin-tx is covered in bitcoin-util-test.json , and it's still passing when generating replay protected signatures.

Reviewers: freetrader, sickpig, kyuupichan, awemany, #bitcoin_abc

Reviewed By: freetrader, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D312