streams: refactor LazyTransform to internal/

streams: refactor LazyTransform to internal/

This commit refactors LazyTransform from the crypto implementation
(lib/crypto.js) into an internal module (not publicy accessible) in
internal/streams/lazy_transform.js. This promotes a more modular core
design and removes code bloat in crypto, as LazyTransform didn't
specifically have anything to do with cryptography, but rather a fast
way to support two APIs on a stream.

PR-URL: https://github.com/nodejs/node/pull/2566
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>