Support xz compressed packages (#5513)

## Summary

Closes #2187.

The [xz
backdoor](https://gist.github.com/thesamesam/223949d5a074ebc3dce9ee78baad9e27)
is still fairly recent, but luckily the [Rust `xz2` crate bundles
version 5.2.5 of the C `xz`
package](https://github.com/alexcrichton/xz2-rs/tree/main/lzma-sys),
which is before the backdoor was introduced.

It's worth noting that a security risk still exists if you have a
compromised version of `xz` installed on your system, but that risk is
not introduced by `uv` or the Rust packages in general.

## Test Plan

Tried installing the package mentioned in the linked issue: `python-apt
@
https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/python-apt/2.7.6/python-apt_2.7.6.tar.xz`

(Note that this will only work on Ubuntu - I tried on a Mac and while
the archive was extracted properly, the package did not install because
of some missing files)

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/uv-extract/src/stream.rs

@@ -198,7 +198,25 @@ pub async fn untar_zst<R: tokio::io::AsyncRead + Unpin>(
     Ok(untar_in(&mut archive, target.as_ref()).await?)
 }
 
-/// Unzip a `.zip`, `.tar.gz`, or `.tar.bz2` archive into the target directory, without requiring `Seek`.
+/// Unzip a `.tar.xz` archive into the target directory, without requiring `Seek`.
+///
+/// This is useful for unpacking files as they're being downloaded.
+pub async fn untar_xz<R: tokio::io::AsyncRead + Unpin>(
+    reader: R,
+    target: impl AsRef<Path>,
+) -> Result<(), Error> {
+    let reader = tokio::io::BufReader::new(reader);
+    let decompressed_bytes = async_compression::tokio::bufread::XzDecoder::new(reader);
+
+    let mut archive = tokio_tar::ArchiveBuilder::new(decompressed_bytes)
+        .set_preserve_mtime(false)
+        .build();
+    untar_in(&mut archive, target.as_ref()).await?;
+    Ok(())
+}
+
+/// Unzip a `.zip`, `.tar.gz`, `.tar.bz2`, `.tar.zst`, or `.tar.xz` archive into the target directory,
+/// without requiring `Seek`.
 pub async fn archive<R: tokio::io::AsyncRead + Unpin>(
     reader: R,
     source: impl AsRef<Path>,
@@ -258,5 +276,20 @@ pub async fn archive<R: tokio::io::AsyncRead + Unpin>(
         return Ok(());
     }
 
+    // `.tar.xz`
+    if source
+        .as_ref()
+        .extension()
+        .is_some_and(|ext| ext.eq_ignore_ascii_case("xz"))
+        && source.as_ref().file_stem().is_some_and(|stem| {
+            Path::new(stem)
+                .extension()
+                .is_some_and(|ext| ext.eq_ignore_ascii_case("tar"))
+        })
+    {
+        untar_xz(reader, target).await?;
+        return Ok(());
+    }
+
     Err(Error::UnsupportedArchive(source.as_ref().to_path_buf()))
 }