[Mailer][Mime] Refactor S/MIME encryption handling in `SMimeEncryptionL…

[fabpot]

Q	A
Feature PR	symfony/symfony#59831
PR author(s)	@Spomky
Merged in	7.3

We created this issue to not forget to document this new feature. We would really appreciate if you can help us with this task. If you are not sure how to do it, please ask us and we will help you.

To fix this issue, please create a PR against the 7.3 branch in the symfony-docs repository.

Thank you! 😃

[alamirault]

@Spomky What is the expected value for repository ? Description is Path to the S/MIME certificate repository. Shall implement the Symfony\Component\Mailer\EventListener\SmimeCertificateRepositoryInterface. Isn't a service id inseated ? I didnt' see real example in PR

Documentation to update: d87be4e