Summary:
Ref T8434. Minor cleanup/modernization. I made type selection modal (like Herald, Auth, etc) so we can render the form on the next screen based on the type.
{F472519}
Test Plan: Created a new source, edited an existing source.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T8434
Differential Revision: https://secure.phabricator.com/D13161
837e6b5ca7