R1:2b5bf4b911ea

Allow "bin/mail send-test" to accept raw email addresses via "--to"

Summary: Ref T12372. This supports testing the `wordwrap()` patch discussed in that task.

Test Plan:
- Ran `bin/mail send-test --to email@domain.com`
- Ran `bin/mail send-test --to username`

Reviewers: chad, lvital

Reviewed By: lvital

Maniphest Tasks: T12372

Differential Revision: https://secure.phabricator.com/D17489