Brand Store - Add a way to define the email "Subject" of the invitation email when creating an email template

Who would benefit?

As a Brand Store admin user, I would like to define the text that should be used as email "Subject" for the invitation email when setting up the email template that should be used when sending the invitation email to brand store users.

What impact would it make?

Users that gets invited to a Brand Store will get a more specific text as the email "subject" when receiving the email which makes it more likely that they will read and understand why they get this email.

How should it work?

Make it possible to define what text to use as the email subject when defining an email template in the Brand Store manager.

Why is it needed?

If the subject of the email is not clear we risk that the user that gets invited to a Brand Store doesn't open the email and miss the invitation.