Add array-based chunks and windows from slices

[cuviper]

pub trait ParallelSlice<T: Sync> {
    fn par_array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>;
    fn par_array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>;
}
pub trait ParallelSliceMut<T: Send> {
    fn par_array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>;
}

[nikomatsakis]

looks good!

[cuviper]

My only hesitation is to wait for std stabilization: rust-lang/rust#74985 and rust-lang/rust#75027

[pittengermd]

Any update on when this pull request might be merged? I would love to use this for video format conversion.

[cuviper]

I'm still hoping std will settle its API, so we can be consistent in how we replicate it here.