Issue #2030597 by adci_contributor, larowlan, daffie, Thomas Brekelmans, boztek, chakrapani, InternetDevels, robbertnl, basvanderheijden: Expand BlockContent and BlockContentType with methods

Issue #2355909 by penyaskito, alexpott, Gábor Hojtsy, DuaelFr: language.settings config is not scalable

Issue #2345793 by tim.plunkett | xjm: Entities should provide a method for a properly generated link to the entity.

Issue #2022875 by Berdir, alexpott, Xano, swentel, tim.plunkett, vladan.me: Resolve difference between submitForm(), submit(), and save() in EntityFormController.

Issue #1966436 by naveenvalecha, cesarmiquel, Berdir, mr.york, jlbellido, segi, vasi1186, Leksat, Gábor Hojtsy, Schnitzel, grisendo, Aron Novak, likin, penyaskito, vijaycs85, kfritsche, fago: Fixed Default *content* entity languages are not set for entities created with the API.

Issue #2272481 by herom, ParisLiakos, tim.plunkett: Remove usages of watchdog() from forms, plugins and controllers.

Issue #1920862 by martin107, Mixologic, cilefen, larowlan, xan.ps, tim.plunkett | sun: Rename custom_block.module to block_content.module.

Issue #2190313 by pfrenssen, Berdir, amateescu, ianthomas_uk: Add $EntityType::load() and loadMultiple() to simplify loading entities.

Issue #1709960 by Berdir, zserno, jessebeach | joachim: Declare a maximum length for entity and bundle machine names.

Issue #2045931 by Sam152, joelpittet, LinL, Sutharsan, adsw12: Replace all module_exists() deprecated function calls.

Issue #1983682 by tim.plunkett, h3rj4n, larowlan: Convert applicable custom_block_menu() entries to use _entity_form() in routing.yml.

This reverts commit c4e52bb6.

Issue #1913618 by tim.plunkett, amateescu: Convert EntityFormControllerInterface to extend FormInterface.