Issue #2008356 by dawehner, tim.plunkett: Provide a _entity_list() route default to replace Controller\EntityListController and mimic _entity_form().
Issue #1913618 by tim.plunkett, amateescu: Convert EntityFormControllerInterface to extend FormInterface.
Issue #1924992 by tim.plunkett, kim.pepper, damiankloip, amateescu: Convert user's system_config_form() to SystemConfigFormBase.
Issue #1915774 by tim.plunkett, amateescu, Crell, dawehner: Decide whether core route controllers should generally/always be DIC services or not.
Issue #1793520 by disasm, klausi, tnightingale, Crell: Add access control mechanism for new router system.