Issue #2089627 by tim.plunkett: Move \Drupal\system\SystemConfigFormBase to \Drupal\Core\Form\ConfigFormBase.
Issue #1981368 by tim.plunkett, Crell, webchick: Convert all routes to 'module_name().foo_bar()' naming convention.
Issue #2003482 by pwolanin, jhodgdon, kim.pepper, Nick_vh, tim.plunkett, jibran, Berdir, effulgentsia, alexpott: Convert hook_search_info() to plugin system.
Issue #2073813 by pwolanin, dawehner, tstoeckler, twistor: Add a UrlGenerator helper to FormBase and ControllerBase.
Issue #1933518 by ACF, pwolanin, mparker17: Convert search's system_config_form() to SystemConfigFormBase.