Issue #3029405 by amateescu, hchonov: Clean up documentation and type hints that don't need to mention both EntityInterface and another specialized interface anymore

Issue #2924724 by plach, hchonov, timmillwood, Gábor Hojtsy, amateescu, gabesullice, catch: Add an API to create a new revision correctly handling multilingual pending revisions

Issue #2926483 by plach, amateescu, effulgentsia, xjm, Sam152, timmillwood, jibran, larowlan, Gábor Hojtsy: Add API methods for determining whether an entity object is the latest (translation-affecting) revision

Issue #2926540 by amateescu, plach, xjm, hchonov, Berdir: Split revision-handling methods to a separate entity storage interface