- Clones when the kind is INLINE or STATIC are sped up by over double.
- Clones when the kind is ARC are spec up by about 1/3.

The previous implementation didn't factor in a single `Bytes` handle
being stored in an `Arc`. This new implementation correctly impelments
both `Bytes` and `BytesMut` such that both are `Sync`.

The rewrite also increases the number of bytes that can be stored
inline.