Support lzma-rs

[konstin]

Would it be possible to support lzma-rs as an alternative to liblzma-sys?

https://github.com/Portable-Network-Archive/liblzma-rs has a single maintainer and a C submodule, which makes it hard for us to review and trust the crate (https://github.com/Nullus157/async-compression/pull/288). lzma-rs is written entirely in safe Rust, which makes it much easier for us to verify, and it also avoids another C dependencies and its (static) linking workarounds.

[NobodyXu]

We are willing to support it behind feature gate lzma-rs

[NobodyXu]

We don't actually need the async_compression_unstable, as we can just use lzma-rs if the feature is enabled

[nilskch]

I would like to take a stab at this. Can you give me some pointers?

[NobodyXu]

Thanks, the codec for lzma is stored in src/codec/xz2, it uses lzma stream for decoding/encoding

Edit: fix the link