feat: Email option in `occ user:add` command

[kyteinsky]

• Resolves: #25319

Summary

Builds upon #29368

This adds an occ command option (email) during the addition of a user to auto-generate a password and send a link to the email address to set a new password if:

1. password-from-env option was not passed
2. email is given and valid

Docs

• Related: docs#11160

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• [x] Tests (unit, integration, api and/or acceptance) are included
• [ ] Screenshots before/after for front-end changes
• [x] Documentation (manuals or wiki) has been updated or is not required
• [ ] Backports requested where applicable (ex: critical bugfixes)