[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