[eCash dev libraries] [p11 ecash-ops] Update ecash-minimaldata for correct dependencies

Summary:
T2847

Depends on D12867

Now that pushdata-ecash is published to npm, replace pushdata-bitcoin with pushdata-ecash in ecash-minimaldata

Update CHANGELOG.md, README.md, and references to dependencies in index.js

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12868