zlib: refactor zlib internals

Split out things that are specific to zlib as a specific
compression library, vs. the interface that is common to
most C compression libraries.

This should pave the way for including support for e.g.
brotli.

PR-URL: https://github.com/nodejs/node/pull/23360


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>