[ecash-lib] Copy chronik to docker image

Summary: Address latest observed CI failure for npm publication of ecash-lib

Test Plan: docker build -f ecash-lib.Dockerfile -t ecash-lib_local .

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16138