Issue #2843770 by Wim Leers, vaplas: EntityResource: Provide comprehensive test coverage for ResponsiveImageStyle entity

Issue #2843779 by vaplas, Yogesh Pawar: EntityResource: Provide comprehensive test coverage for ShortcutSet entity

Issue #2843786 by arshadcn: EntityResource: Provide comprehensive test coverage for ImageStyle entity

Issue #2843759 by vaplas, Wim Leers: EntityResource: Provide comprehensive test coverage for SearchPage entity

Issue #2113345 by dawehner, tedbow, Wim Leers, kristiaanvandeneynde, Crell, Grayside, klausi: Define a mechanism for custom link relationships