[explorer and ecash-herald] Parse new miner nodeStratum
Summary: Parse new miner in ecash-herald and explorer.e.cash
Test Plan: npm test for ecash-herald, cargo test for explorer.e.cash
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D16586