Rename useFacetEffect to useFacetLayoutEffect and add a new useFacetEffect

[jacobbergdahl]

The name of the useFacetEffect function is slightly misleading in the current implementation, as it is actually using React's useLayoutEffect as an underlying function. Thus, we have renamed the function to useFacetLayoutEffect and added a new function called useFacetEffect in its place that actually uses React's useEffect.

We have updated the documentation to reflect this change in a separate pull request (#31).

[jacobbergdahl]

There is now a handful of code that is duplicated between useFacetEffect and useFacetLayoutEffect. @MartinMoe and I had a discussion about whether we should extract parts of the code into shared functions. We could even combine certain tests or make parts of the implementation of the tests reusable between useFacetEffect and useFacetLayoutEffect.

We ended up deciding not to do so for now, however. We decided to prioritized keeping the code easily readable and to keep the logic between different functions completely separated, even if it is similar.