* Support user-provided font-fallback.
* Use tonic to pass to native
* Handle font families as a fallback vector in LibTxt
* Fix docs
* Concatentate fontFamily lists in dart before passing to engine
* Fix formatting
* Reworked font family matching to search all managers
* Fix formatting
* Proper toString null checking to keep format consistent
* Formatting
* Move _listEquals out of textstyle as it is not specific to TextStyle and will later be used for paragraphStyle too