Issue #3483146 by nicxvan, sourav_paul, vladimiraus, mstrelan, smustgrave: Add string return type to all hook_help implementations

Issue #3488823 by mstrelan, shalini_jha, smustgrave, nicxvan: Add void return to @ingroup entity_crud hook implementations

Issue #3488109 by mstrelan, quietone: Add AccessResultInterface return type to hook_entity_access (and friends) implementations

Issue #3489519 by mstrelan, smustgrave, quietone: Add void return to module and theme install/uninstall hook implementations

Issue #3483599 by nicxvan, ghost of drupal past, catch, longwave, fabianx: Convert all procedural hook implementations to Hook classes