extract, list: auto-detect and decompress gzip archives

[kevinburke]

Previously, extract and list passed the raw file bytes directly to the tar parser without decompression. When given a .tar.gz file, the compressed gzip stream was interpreted as tar headers, producing errors like "numeric field did not have utf-8 text" on the checksum field.

Detect gzip compression by reading the two-byte magic number (0x1f 0x8b) at the start of the file, and wrap the reader in a GzDecoder when present. Plain .tar files continue to work as before.

Confirmed this patch allows extraction of Go source code from https://go.dev/dl/ (previously we would get an error).

[codecov]

Codecov Report

❌ Patch coverage is 96.31148% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.54%. Comparing base (2c7a5e6) to head (63389ab).
⚠️ Report is 29 commits behind head on main.

Files with missing lines	Patch %	Lines
src/uu/tar/src/compression.rs	83.92%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #168       +/-   ##
===========================================
+ Coverage   60.83%   96.54%   +35.70%     
===========================================
  Files           7       10        +3     
  Lines         789     1157      +368     
  Branches       24       26        +2     
===========================================
+ Hits          480     1117      +637     
+ Misses        309       39      -270     
- Partials        0        1        +1     

Flag	Coverage Δ
macos_latest	96.54% <96.31%> (+35.70%)	⬆️
ubuntu_latest	96.54% <96.31%> (+35.70%)	⬆️
windows_latest	0.00% <0.00%> (ø)

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[kaladron]

Hi Kevin! I'm holding this for just a bit while I get the support for reading from stdin in as that will change some function interfaces. I'll review this right after.

[kaladron]

Please tage #158 in the commit description.

[kevinburke]

I see quite a lot of patches just came in; anything I can help review?

[kaladron]

I see quite a lot of patches just came in; anything I can help review?

I filed Issues for each piece of missing functionality so that we can coordinate. If more people are showing up, I want them to be able to claim an issue rather than have any conflict. But I'll tag you in two others (that are blocking these at the moment)