Allow to import database from Ysul on dbserver-mysql role

Summary:
Ysul has 255 databases, created between 2001 and now.

Instead of blindly restore everything, the idea is to provide
the dumps in /var/backups/db-treasure-chest directory, and a script
to create and restore the database on request.

Usage: db-treasure-import <database name>

Ref 1803

Test Plan: Deploy on db-B-001, import a database

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2985