Translate email notification templates

@yivanov thank you for the nice work!

What's missing I guess is an update hook transfering the config values into the newly created config!
Also could you please create this as MR instead of a patch?

Happy to review again, thank you!

Yep, the patch doesn't apply any more. Maybe @yivanov could give a new, adjusted version of the patch as an MR on the current issue fork!

I don't think we need to change the configuration structure, unless I miss something?

Switching from string to label or translatable text should be enough.

And would facilitate its merging.

Just created an MR based on @yivanov patch without changing the configuration structure.

Any feedback is welcome.