9aa5a8cb7b
Summary: Ref T2787. Instead of making providers global configuration, make them a thing on merchants with web configuration. Payment methods and some of the pyament workflow needs to be retooled a bit after this, but this seemed like a reasonable cutoff point for this diff. Test Plan: See screenshots. Reviewers: btrahan Reviewed By: btrahan Subscribers: epriestley Maniphest Tasks: T2787 Differential Revision: https://secure.phabricator.com/D10649