Issue #1916790 by plach, YesCT, penyaskito, Gábor Hojtsy, das-peter, herom, larowlan: Convert translation metadata into regular entity fields

Issue #2227973 by pfrenssen, Berdir: Rename ContentTranslationController to ContentTranslationHandler.

Issue #1968970 by plach: Standardize module-provided entity info documentation and clean-up the @EntityType annotation.

Issue #1810350 by plach, kfritsche, boran, YesCT: Remove menu_* entity keys and replace them with entity links.

Issue #2066535 by tim.plunkett, jsst, Berdir: Add EntityManagerInterface and stop typehinting with EntityManager.

Issue #1810330 by c4doug, plach, YesCT: Remove EntityTranslationControllerInterface::removeTranslation().

Issue #1810320 by alarcombe: Remove EntityTranslationControllerInterface::getAccess() once have entity access.

Issue #1807042 by tim.plunkett, effulgentsia: Rename entity storage/list/form/render controllers to handlers, part 1: organize existing annotation keys.

Issue #1446382 by plach: Need a reliable way to determine if a specific bundle for an entity type is translatable.

Issue #1807776 by plach, Berdir, YesCT, Gábor Hojtsy, bforchhammer, Bojhan, webchick: Support both simple and editorial workflows for translating entities.

Issue #1188388 by plach, peximo, YesCT | Gábor Hojtsy, fago, webchick, Bojhan, podarok, cosmicdreams, Berdir, aspilicious, bforchhammer, penyaskito: Added Entity translation UI in core.