Separator for navbars-links

Is your feature request related to a problem? Please describe. As a user I like to separator the links with a character like in this sample: https://mjml.io/try-it-live/7x_kTC0GCH

Describe the solution you'd like As a user I like to add the separator as a parameter to the navbar. The separator should only be added between navbar-links. If navbar breaks into two lines (e.g. by screensize) you do not like one separator to be at the begining or end of a line (try mobile preview in above sample two see the problem).

Describe alternatives you've considered As of today we add separators as mj-navbar-links by hand as in sample above.