- always support conversion from alloc::Vec for VecConfigNew?

- inline box:
  Box::new_in(value, Inline)
  Vec::new_in(InlineArray<N>)
  Box::new_in

- RawAlloc -> ByteAlloc/MemoryAlloc/LayoutAlloc

- SizedAlloc<T>

- ArrayAlloc<T, I> used by vec and Box::new_uninit_slice?
  type ArrayBuffer { capacity() } + RawBuffer<T>
  -> implemented for all RawAlloc
  -> caller must store capacity
  -> try_new_array(count: I) -> NonNull<[T]> and release_array(ptr, count: I)

- VecAlloc<T, I>
  -> implemented for all ArrayAlloc by adding length to handle
  -> buffer must also handle length
  -> Thin requires a special buffer -> does not implement ArrayAlloc?
  -> Any 'ArrayAlloc' buffer would need to provide the capacity
     and the handle or buffer would need to store the length

- new_in for Box<[T]>?
