incorporate `nplrt()` hypothesis testing function into main `happi()` function 

Currently the main `happi()` function performs and outputs the asymptotic testing. There is a separate function `npLRT()` that needs to be integrated into the main `happi()` function so users can call this permutation hypothesis testing approach easily instead of having to feed in a `happi` results object to the `npLRT` function to get the permutation results. 