migrate-dart-helper-utils-v6-to-v7

Use when upgrading a project from dart_helper_utils 6.x to 7.x, or fixing analyzer errors and deprecation warnings after that bump - isAtSameDayAs/addOrSubtractMonths/tomorrow/isPresent/formatASyQQQ/enforceRtlIn/swap/find renames, String isEmptyOrNull to isBlank, Dart 3.13.5 and stringo 3 requirements, the removed Iterable.find, int statistics now returning double, mask and insert returning String?, UTC and daylight-saving changes in date helpers, isDOCX/isXLSX precision, typed Debouncer executionHistory, DebouncerState no longer being Equatable, or test values that changed because 7.0 fixed a bug.