use zlib-rs for gzip compression in rust code (#15417)

### What does this PR try to resolve?

This PR uses `zlib-rs` via the `flate2` crate. It is used for
(de)compressing gzip files (e.g. in `cargo package`).

Using zlib-rs is significantly faster, and produces output of roughly
similar size. For the `windows-bindgen` crate
(a very large crate), the speedup is over 60%, or about 2 seconds.

```
> time cargo package -p windows-bindgen --no-verify
   Packaging windows-bindgen v0.61.0 (/home/folkertdev/rust/windows-rs/crates/libs/bindgen)
    Updating crates.io index
    Packaged 76 files, 31.2MiB (8.2MiB compressed)

________________________________________________________
Executed in    3.30 secs    fish           external
   usr time    3.19 secs  424.00 micros    3.19 secs
   sys time    0.05 secs   61.00 micros    0.05 secs

> time ~/rust/cargo/target/release/cargo package -p windows-bindgen --no-verify
   Packaging windows-bindgen v0.61.0 (/home/folkertdev/rust/windows-rs/crates/libs/bindgen)
    Updating crates.io index
    Packaged 76 files, 31.2MiB (8.3MiB compressed)

________________________________________________________
Executed in    1.25 secs    fish           external
   usr time    1.15 secs    0.00 micros    1.15 secs
   sys time    0.04 secs  589.00 micros    0.04 secs
```

### How should we test and review this PR?

Generally CI/the test suite should handle correctness.

Something to look out for is zlib-rs producing larger binaries than
before. So far we're seeing output sizes that are roughly the same
(sometimes a bit better, sometimes a bit worse) as the status quo.

We've not specifically looked at decompression yet, mostly because we
could not come up with a good command to benchmark. In general zlib-rs
is much faster than stock zlib there too.

### Additional information

For the time being, `cargo` still depends on stock zlib via e.g. `curl`
and `git`. As far as I know it is the intention to eventually move away
from these C dependencies, at which point the dependency on stock zlib
also disappears.

Author: epage

Cargo.lock

@@ -45,7 +45,7 @@ criterion = { version = "0.5.1", features = ["html_reports"] }
 curl = "0.4.47"
 curl-sys = "0.4.79"
 filetime = "0.2.25"
-flate2 = { version = "1.0.35", default-features = false, features = ["zlib"] }
+flate2 = { version = "1.1.1", default-features = false, features = ["zlib-rs"] }
 git2 = "0.20.0"
 git2-curl = "0.21.0"
 # When updating this, also see if `gix-transport` further down needs updating or some auth-related tests will fail.

Cargo.toml

@@ -57,7 +57,7 @@ The build will automatically use vendored versions of the following libraries. H
 * [`libcurl`](https://curl.se/libcurl/) — Used for network transfers.
 * [`libgit2`](https://libgit2.org/) — Used for fetching git dependencies.
 * [`libssh2`](https://www.libssh2.org/) — Used for SSH access to git repositories.
-* [`libz`](https://zlib.net/) (aka zlib) — Used for data compression.
+* [`libz`](https://zlib.net/) (AKA zlib) — Used by the above C libraries for data compression. (Rust code uses [`zlib-rs`](https://github.com/trifectatechfoundation/zlib-rs) instead.)
 
 It is recommended to use the vendored versions as they are the versions that are tested to work with Cargo.
 

README.md

@@ -187,7 +187,7 @@ The [`default` features](#the-default-feature) can be disabled using
 
 ```toml
 [dependencies]
-flate2 = { version = "1.0.3", default-features = false, features = ["zlib"] }
+flate2 = { version = "1.0.3", default-features = false, features = ["zlib-rs"] }
 ```
 
 > **Note**: This may not ensure the default features are disabled. If another