804: An external dependency registry and name mapping mechanism

Co-authored-by: Pradyun Gedam <pradyunsg@gmail.com>
Co-authored-by: rgommers <ralf.gommers@gmail.com>
Co-authored-by: mgorny <mgorny@users.noreply.github.com>
Co-authored-by: Mike Sarahan <msarahan@gmail.com>

Author: 5 people