This reverts commit 82bece91.

Issue #2716081 by timmillwood, dixon_: BlockContent should have revision_user and revision_created fields and implement RevisionLogInterface

Issue #2707255 by timmillwood, dawehner, amateescu, Berdir: All content entities should inherit baseFieldDefinitions

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

Issue #2529892 by larowlan, stefan.r, Berdir, almaudoh: BlockContentForm uses form validation instead of a validation Constraint

Issue #1314214 by stefan.r, phayes, ergophobe, YesCT, damienwhaley, kbasarab, Tor Arne Thune, basic, pfrenssen, yannickoo, simolokid, fietserwin, bzrudi71: MySQL driver does not support full UTF-8 (emojis, asian symbols, mathematical symbols)

Revert "Issue #1314214 by stefan.r, phayes, ergophobe, YesCT, damienwhaley, Tor Arne Thune, kbasarab, pfrenssen, basic, yannickoo, simolokid: MySQL driver does not support full UTF-8 (emojis, asian symbols, mathematical symbols)"

This reverts commit b105158a.

Issue #1314214 by stefan.r, phayes, ergophobe, YesCT, damienwhaley, Tor Arne Thune, kbasarab, pfrenssen, basic, yannickoo, simolokid: MySQL driver does not support full UTF-8 (emojis, asian symbols, mathematical symbols)

Issue #2428795 by mkalkbrenner, plach, yched, catch, hchonov, webchick, tstoeckler, pjonckiere, miro_dietiker, Schnitzel, klausi: Translatable entity 'changed' timestamps are not working at all

Issue #2281645 by dawehner, andypost: Make entity annotations use link templates instead of route names

Issue #2143729 by tstoeckler, plach, jsbalsera, Berdir, mauzeh, damiankloip, andypost: Entity definitions miss a language entity key

Issue #2284917 by Wim Leers, larowlan, olli: In-place editing of custom blocks broken *again* (because attributes and contextual links of custom blocks are lost)

Issue #2230637 by plach, fran seva, yched, swentel: Create a Language field widget and the related formatter

Issue #2100343 by Berdir, fago, martin107, visabhishek, sriharsha.uppuluri, Yorirou: Remove 'fieldable' key in entity definitions in favour of 'field_ui_base_route'.

Issue #2313757 by Berdir, Wim Leers, dawehner: Remove text_processing option from text fields, expose existing string field types as plain text in UI.

Issue #2326949 by plach, effulgentsia: Move entity-type-specific schema information from the storage class to a schema handler.

Issue #1976158 by Berdir | msonnabaum: Rename entity storage/list/form/render "controllers" to handlers.

Issue #2154435 by andypost, Berdir, mparker17: Rename EntityAccessController to EntityAccessControlHandler.

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

Issue #2248991 by marco, tstoeckler, xjm: Rename the 'log' field to 'revision_log' in Node and CustomBlock.

Issue #2183231 by tstoeckler, plach, jessebeach, fago, Berdir, xjm, mauzeh: Make ContentEntityDatabaseStorage generate static database schemas for content entities.