fix(cp): continue traversal on NotFound error

[nekluu]

Description

This PR addresses a TODO in copy_direntry regarding error handling during directory traversal.

Currently, if a file is missing (e.g., deleted by another process) during a copy operation, cp terminates immediately. This change allows cp to show a warning and continue with the remaining files when a NotFound error occurs, consistent with how PermissionDenied is handled.

Changes

• Added a match arm for io::ErrorKind::NotFound in copy_direntry.
• Ensured the process continues instead of returning an Err early.

Related Issue

Addresses the TODO comment in src/uu/cp/src/copydir.rs.

[Ecordonnier]

"Related Issue
Addresses the TODO comment in src/uu/cp/src/cp.rs."

-> what do you mean? The TODO this PR addresses is in copydir.rs, not in cp.rs.

Also since this PR addresses the TODO, can the TODO now be removed?

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/shuf/shuf-reservoir (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/sort/sort-stale-thread-mem (passes in this run but fails in the 'main' branch)

[codspeed-hq]

Merging this PR will degrade performance by 26.25%

❌ 7 regressed benchmarks
✅ 275 untouched benchmarks
⏩ 38 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	sort_mixed_data[500000]	22.5 MB	27.2 MB	-17.15%
❌	Memory	sort_ascii_only[500000]	22.2 MB	28.3 MB	-21.74%
❌	Memory	sort_long_line[160000]	724.4 KB	982.3 KB	-26.25%
❌	Memory	sort_accented_data[500000]	22.1 MB	28.3 MB	-21.78%
❌	Memory	sort_key_field[500000]	45.8 MB	51.8 MB	-11.46%
❌	Memory	cp_large_file[16]	107.6 KB	116.9 KB	-8%
❌	Simulation	cp_large_file[16]	369.8 µs	383.3 µs	-3.52%

---

_{Comparing nekluu:main (9ad27a2) with main (799de29)}

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. ↩

[nekluu]

"Related Issue Addresses the TODO comment in src/uu/cp/src/cp.rs."

-> what do you mean? The TODO this PR addresses is in copydir.rs, not in cp.rs.

Also since this PR addresses the TODO, can the TODO now be removed?

I apologize, I wrote the file path incorrectly. My mistake. I keep the TODO because I thought you might want to support other error types in the future. If you think no further error support is needed, we can remove the TODO.