build: Move interfaces/* to libbitcoin_server

Summary:
Backport of Core PR 14204
https://github.com/bitcoin/bitcoin/pull/14204/files
Fixes cmake build issue where interfaces/wallet.cpp wasn't linking correctly in D2817

Test Plan: Build D2817 with this diff applied instead of the linking attempts included in that diff.

Reviewers: deadalnix, Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D2842