migrate-dart-helper-utils-v5-to-v6

Use when upgrading a project from dart_helper_utils 5.x or earlier to 6.x, or fixing compile errors after that bump - ConvertObject/toString1/ParsingException renames, altKeys to alternativeKeys, firstValueForKeys to tryGetRaw, removed Paginator/DoublyLinkedList/country data/StringSimilarity, httpFormat to httpDateFormat, encodedJsonString to toJsonString, TimeUtils.throttle signature change, percentile 0-100 range, delay methods, or helpers that moved to convert_object or package collection.