Allow Kunena's translation of menus via language constants

[universewrld]

Is your feature request related to a problem? Please describe.
Currently, to translate the menu items of the Kunena forum (if the site has 2 or more languages), you need to create new menu items.

Describe the solution you'd like
Allow Kunena's translation of menus via Language Constants. Thus, it will not be necessary to create new menu items in another language (if the site has 2 or more languages).

Describe alternatives you've considered
I saw that this method for translating the menu is used in @jomsocial and I really liked this way, it's really amazing!

Additional context
I think it would be very great if we could do the same way of translating menu items in the Kunena forum!

[810]

duplicated issue: #628

closing this one.