[token-server] Use ecash-coinselect from npm

Summary: Build is failing here in CI, looks related to the local dep. Will troubleshoot later as want to get all pkgs on this, but for now want to see if that's really the issue.

Test Plan: confirm dep change.

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D16013