Support client_max_window_bits and server_max_window_bits compression options

[hexdigest]

This is related and fixes #443

[hexdigest]

Hey guys these ☝️ are failing due to thirdparty dependency.

@nhooyr the third party dependency I introduce here is a well known drop in replacement for compress/flate. It also has constructors that allows you to specify the size of the window.

[mafredri]

Hey @hexdigest. Thanks for the contribution! I'll need to read up on this a bit to give a proper review, so it might take a while.

In the meantime, I'm thinking an implementation that allows providing a custom flate implementation via options would be preferable. This way we don't need to add any external dependencies to this library, yet we support the use-case. It'd be fine to even include an example of how to do it as part of the go docs.