long term goal: Migrate all native code to rust

[nyancrimew]

The current native dictionary implementation feels dirty, is riddled with TODOs and can probably be improved a lot if only it were in a language i actually understand that also provides much more safety. It's also most likely required that we do modifications to it anyways if we want to implement future features such as multilingual typing, more advanced predictions and potential support for gboard dictionaries ("dictionary v3").

In a first step we should try porting the dictionary tools to rust, to get a better understanding of dictionary internals in general and to get a sense of the scale of this project.