Issue #2670730 by chr.fritsch, robpowell, alexpott, tstoeckler, Berdir, bojanz, dawehner: Provide a delete action for each content entity type

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2666792 by bojanz, dawehner, edysmp, heddn: Provide a route provider for add-page of entities

Issue #2578955 by dawehner, jhodgdon, Wim Leers, catch: Implement auto route generation but DON'T use it for all core entities