[alias-server] Add new database function to lookup registered aliases by address

Summary:
T3060

Add a new database function to look up registered aliases by address. This will be used to build an API endpoint.

Test Plan: npm test

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D14130