Get 'test' working properly with acls and supplementary groups

[jefft]

Fixes #8960 and #9147. Delegate to libc euidaccess to avoid bugs (#9147) and respect ACLs (#8960).

Note, the tests are independent commits that can be applied first, where they should fail before the 'fix' commit is applied. Run the tests with:

cargo test --test tests test_permission_with_acl
cargo test --test tests test_permission_with_supplementary_group

Warning: code is partly Claude-generated as I'm not that familiar with Rust.

[codspeed-hq]

Merging this PR will degrade performance by 27.39%

❌ 8 regressed benchmarks
✅ 274 untouched benchmarks
⏩ 38 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	sort_long_line[160000]	712.6 KB	981.4 KB	-27.39%
❌	Memory	sort_accented_data[500000]	22.1 MB	28.3 MB	-21.79%
❌	Memory	sort_mixed_data[500000]	22.9 MB	27.1 MB	-15.71%
❌	Memory	sort_key_field[500000]	47.8 MB	51.8 MB	-7.62%
❌	Memory	sort_unique_locale[500000]	33.6 MB	39.8 MB	-15.51%
❌	Memory	sort_numeric[500000]	75.5 MB	79.2 MB	-4.66%
❌	Memory	sort_ascii_only[500000]	22.2 MB	28.3 MB	-21.77%
❌	Memory	du_wide_tree[(5000, 500)]	1.2 MB	1.3 MB	-3.86%

---

_{Comparing jefft:fix/8960-9147-test-work-with-acls-and-supplementary-groups (09b1211) with main (a1545ef)}

Footnotes

1. 38 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/tee (fails in this run but passes in the 'main' branch)

[sylvestre]

dunno if you saw it but many jobs are failing, this is why it hasn't been reviewed yet

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/cp/cp-mv-enotsup-xattr. tests/cp/cp-mv-enotsup-xattr is passing on 'main'. Maybe you have to rebase?
Note: The gnu test tests/csplit/csplit-io-err was skipped on 'main' but is now failing.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/tail/assert is no longer failing!

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)