Issue #2375589 by larowlan, pameeela, jibran, kim.pepper, Wim Leers, Bojhan: Convert custom block library page to views

Issue #1728804 by Berdir: Introduce (Content)EntityDeleteForm and children to handle entity deletions

Issue #697760 by sun: Replace getInfo() in tests with native phpDoc + annotations (following PHPUnit).

Issue #1912610 by amitgoyal, BryanCGreen24, lokapujya, Rajendar Reddy, echoz, barraponto, LewisNyman, pixelwhip: Rename layout classes to follow the layout style naming convention.

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

Issue #2253735 by larowlan, olli, xjm: Fixed WSOD on custom block creation / listing if config translation enabled.

Issue #2120871 by andypost, Berdir, amateescu, vladan.me, Xano: Rename EntityListController to EntityListBuilder.

Issue #2074037 by Wim Leers, effulgentsia: Add drupalPostUrl() — drupalPost()/drupalPostAjax() are for forms only, D8 JS performs non-form HTTP requests.

Issue #2057869 by dawehner, jibran: Provide an alias for 'plugin.manager.entity' called 'entity.manager'.