Add an algorithm identifier to the nonce generation for ECDSA signatures

Summary:
Adding an algorithm dependent identifier to the nonce seed ensures that
no information can be retrieved when signing with the same key and
different algorithms.

Test Plan:

make check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2193