[refactor] add const CCoinControl& param to SendMoney

Summary:
this was cleaned up in a previous diff but is now a hurdle to
backporting PR13756. this change makes the backport possible and brings
us a tad closer to core for less merge conflicts down the road.

Test Plan:

ninja

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D6367