When users click send email in UI, they need to wait a minute or more to
see some emails started going out.
This commit adds additional trigger into sending queue API.
If emails is set to send it triggers Action Scheduler immediately.
Users will get immediate feedback that emails are sending.
[MAILPOET-4274]
- Rename validator to newsletterValidator for clarity
- Add validation for ALC content
- Refactor tests to use data factory for consistency and to avoid
validation issues
- Add separate tests for NewsletterValidator service
- Add test helper for retrieving service with private properties
overridden by name
[MAILPOET-4236]
