Improve email address parsing

What does this MR do?

If you enter the following RFC 2822 compliant address: John Doe <john@doe.com>

Gitlab will attempt to send three emails:

1. John
2. Doe
3. john@doe.com

With this change, given the following: John Doe <johndoe@example.com> Jane Doe <janedoe@example.com>

Gitlab will send emails to johndoe@example.com and janedoe@example.com

Closes #44676 (closed)

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

See #44676 (closed)

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

#44676 (closed)