Complete the zlib-rs support without the need for C-bindings

[Byron]

This PR adds set_dictionary and set_level to the zlib-rs backend, which is now used directly from Rust, without a detour through C-bindings.

Followed up by #525 .

[Copilot]

Pull request overview

This PR completes zlib-rs support by adding set_dictionary and set_level methods that call zlib-rs directly without requiring C-bindings. The implementation maintains separate counters to track total input/output bytes excluding dictionary data, consistent with the existing C backend approach.

Key Changes:

• Added native set_dictionary and set_level support for zlib-rs backend
• Implemented separate total_in/total_out tracking to exclude dictionary bytes from counts
• Updated zlib-rs dependency from version 0.5.3 to 0.5.4

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
Cargo.toml	Updated zlib-rs dependency from 0.5.3 to 0.5.4 to support new API features
src/mem.rs	Added set_dictionary methods for zlib-rs backend and refactored set_level to support both any_zlib and zlib-rs; updated test configuration for error message test
src/ffi/zlib_rs.rs	Added total_in/total_out tracking fields, implemented set_dictionary and set_level methods, and updated error handling to use error_message() from inner state

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[joshtriplett]

LGTM. Thank you for refactoring and cleaning up.

[Byron]

Thanks a lot!

I rebased #525 on top of main, acting as regression protection. During our previous attempt to release zlib-rs without C-bindings, we accidentally broke a bunch of functionality which now wasn't accessible anymore, and the test-suite couldn't catch it. With #525 that changes.

When that is available, I think a new release should be attempted.