Lang is a url parameter now.

@sibamohanty says: 

Changes made

queryActivated is true all the time.
lang is updated in updateURLQueryParameters 3 .explore view has translation activated.
Over here, the point of redirecting to /set_language/ is that the set language page sets the language cookie and redirects back to the current page. Since we're not relying on the cookie anymore, I think you can do window.location.reload() here and that should work. See if that's true  - I could be wrong. You can then also remove the set_language view and get rid of it from the URLs if that's the case.