Issue #1754246 by webflo, swentel, penyaskito, andypost, alexpott, YesCT, dagmar: Languages should be configuration entities.

Issue #1813762 by ParisLiakos, Jose Reyero, YesCT, japicoder, attiks: Introduce unified interfaces, use dependency injection for interface translation.

Issue #1957154 by joates, ayelet_Cr, xjm | Berdir: Replace calls to drupal_container()->get('module_handler()') service with Drupal::moduleHandler().

Issue #1905152 by Gábor Hojtsy, Jose Reyero, vijaycs85, YesCT, penyaskito: Integrate config schema with locale, so shipped configuration is translated.