Rewrite gzip component to support trailing bytes without external tool and compress with PIGZ. Addresses #476

[alchzh]

• I have reviewed the OFRAK contributor guide and attest that this pull request is in accordance with it.

Rewrite gzip component to support trailing bytes without external tool.

Link to Related Issue(s)

#476
python/cpython#68489

Please describe the changes in your request.

• Replaces the use of the gzip library with calls to the underlying zlib library directly, in a way that doesn't fail with trailing garbage at the end of files.
• Substantially rewrites of gzip test cases to use a common template
  • adds a test for multi member gzip files
  • the trailing bytes test actually tests the unpack

[rbs-jacob]

This needs a changelog entry, but after that, should probably be good to go.

[whyitfor]

See comments.

[alchzh]

Based on benchmarks of zlib module vs pigz, no benefit to using pigz for decompression, but significant benefit to using it for compression.

https://gist.github.com/alchzh/24ca62a6f87548ea2b1911c174e0ed54

[whyitfor]

Looks good to me.

Especially like the profiling and data-driven approach.

[rbs-jacob]

I did not review the tests in great detail, but I like the way that this implementation ended up. Seems like a big improvement!

[rbs-jacob]

I relented and included one minor change that I would like to see before merging this.

[rbs-jacob]

Thanks for this fix. Looks ready to merge once the tests pass!