Feature request: option to set languages at registering

Hello,

I would like to see some kind of option above "The Admin plugin has been installed ..." that changes the back- and frontend language so that right from the start you have your language.

Olli

No files or tests are named. Start by locating the Admin plugin's installation and registration flow, then trace how the back-end and front-end language are selected. Done should mean that a language can be chosen during registration and is applied from the start.

Written by the indexing model from the issue text.