[eCash dev libraries] [p15 ecash ops] Upgrade ecash-ops

Summary:
T2847

Depends on D12881

Fix README links and remove format testing from ecash-ops

Test Plan:
Review readme
Confirm standard library is not used anywhere

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12882