Follow-up for #1754246: Change notice: Languages should be configuration entities
Problem/Motivation
Languages now configuration objects so their routers used own accessChecks
Proposed resolution
Implement LanguageAccessController for Language configurable entity and use it for all access checks
Related Issues
#1946426: Convert all of confirm_form() in language.admin.inc to the new form interface
#2005778: Convert language_admin_overview_form to a Controller