zlib: Add support for info: true option

[npaun]

This PR implements the {info: true} option for zlib. It's not documented for brotli, but the unit tests expect it there too. We return an engine, and the buffer.

However, the engine we're returning isn't really legit - we just create it on the fly to return it. Should we fall back to the streaming path when info: true, for more fidelity with NodeJS or is this close enough? Now going whole-hog and falling back to the streaming implementation when info: true

[anonrig]

We're diverging from node.js zlib implementation and it is producing different states for info: true.

For example, on Node.js

> require('zlib').brotliCompressSync('aaa', { info: true })
{
  buffer: <Buffer 0b 01 80 61 61 61 03>,
  engine: BrotliCompress {
    _writeState: Uint32Array(2) [ 16377, 0 ],

but calling initializing BrotliCompress directly produces different results on writeState

> require('zlib').BrotliCompress({ info: true })
<ref *1> BrotliCompress {
  _writeState: Uint32Array(2) [ 0, 0 ],

[anonrig]

Enum values are not 1 to 1 representably js. We should avoid using them. Can we convert this to an object and move this to the file where it is used?

[npaun]

I moved this enum to internal_zlib.ts, but I was not sure how to replace it with an object, because keyof typeof CLASS_BY_MODE would just be number.

[anonrig]

Let's wait for @jasnell to review, before landing.