[ecashaddrjs] Add unit tests to CI

Summary:
T3044

Add ecashaddrjs unit test to CI

Test Plan: ./contrib/teamcity/build-configurations.py ecashaddrjs-tests

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13677