Add a --force command to `phd start`
Summary:
Ref T7352. This isn't wildly useful for us but seems generally reasonable, can be helpful with testing, and @hach-que has a use case for it.
The only reason we issue this warning is to prevent user error; you can still launch all the daemons with `phd launch` manually and daemons all use locks to protect critical regions.
Test Plan: Ran `phd start --force` a bunch, saw zillions of daemons.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley, hach-que
Maniphest Tasks: T7352
Differential Revision: https://secure.phabricator.com/D11861