Proxy VCS SSH requests
Summary: Fixes T7034. Like HTTP, proxy requests to the correct host if a repository has an Almanac service host.
Test Plan: Ran VCS requests through the proxy.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T7034
Differential Revision: https://secure.phabricator.com/D11543