[feature] Implement rayon::iter::IntoParallelIterator for ArrayVec

[chipshort]

It's currently not easily possible to create a parallel iterator from an ArrayVec<T, C> that yields owned T values.
I think this would be a very neat feature because it makes a lot of sense to collect into an ArrayVec after filtering some iterator, so rayon knows how many items it has to process.
There is already an implementation in #164 that just needs to be updated to the latest arrayvec API. I'd be happy to do that if there is interest in merging it.

There is a similar request for more rayon support in the form of FromParallelIterator