Make email subject translatable

Here is a patch written on top of ✨ Use queue for sending emails Needs review . Since over there I'm working on a major overhaul of the module, it makes no sense to try to fix this for 2.0.x. I'd like to set the version to 2.1.x, but I'm not able to create a dev release for that branch yet.

Hi @megachriz: what's the status of 2.1.x? if you'll release a new version based I'd like to test it. Thank you very much.

@finex
I did not manually test the 2.1.x version on Drupal 11 yet, while the dev version says it is Drupal 11 compatible. See latest comment from 📌 Add Drupal 11 support for 2.1.x branch Needs review . This the main reason that I did not create a release yet.

Additionally, in #2993374-9: Use queue for sending emails → there were some suggestions for improvements that would be nice to haves for 2.1.x. I had suggested to open new issues for these before closing the issue. Not for every suggestion a new issue was created yet.

I also liked ✨ Link to the cart in the email could be non-session dependent Needs review to get in 2.1.x, but that one is also a nice to have.