Expose zlib fine-tuning options in high-level API

[RReverser]

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Just moving from a comment (https://github.com/alexcrichton/flate2-rs/pull/230#issuecomment-592104767) to a proper tracking issue:

@RReverser > @alexcrichton Somewhat related. I've noticed that higher-level APIs currently don't expose these advanced zlib configurations, which seems a shame because they're much easier to use than Compress / Decompress directly, and sometimes you really need that fine-tuning. Would you be open to adding either new methods to ZlibEncoder / ZlibDecoder to propagate corresponding params, or adding implementations of From<Compress> / From<Decompress> so that one could create a high-level wrapper for a preconfigured instance?

@alexcrichton > In terms of adding higher-level APIs, yes, that seems fine to me too. I would prefer it if were a separate PR though and for this to not balloon too much.