use unitful arrays

Inherently RUBIX will work with unitful arrays. Currently, we have fixed the units in the yaml file and do unit conversion manually. However, using [quax](https://github.com/patrick-kidger/quax), [quaxed](https://github.com/GalacticDynamics/quaxed/) and a modification of [coordinax](https://github.com/GalacticDynamics/coordinax/) we might be able to give RUBIX unit support. 
