uucore, expr: centralize regex in uucore

[wtcpython]

No description provided.

[xtqqczze]

perhaps we could move the feature selection to src/uucore/Cargo.toml

[codspeed-hq]

Merging this PR will degrade performance by 3.77%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 14 regressed benchmarks
✅ 353 untouched benchmarks
⏩ 50 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	factor_multiple_u64s[2]	88.8 KB	92.9 KB	-4.4%
❌	Memory	hostname_basic	91 KB	95.1 KB	-4.3%
❌	Memory	seq_custom_separator	93.1 KB	97.2 KB	-4.21%
❌	Memory	wc_lines_extreme_line_lengths[(100000, 200)]	99.7 KB	103.8 KB	-3.94%
❌	Memory	nl_many_lines[100000]	100.9 KB	105 KB	-3.9%
❌	Memory	unexpand_many_lines[100000]	101.7 KB	105.8 KB	-3.87%
❌	Memory	expand_custom_tabstops[50000]	101.7 KB	105.8 KB	-3.86%
❌	Memory	cut_characters_long_lines	103.2 KB	107.3 KB	-3.81%
❌	Simulation	hostname_basic	426.7 µs	443.2 µs	-3.72%
❌	Memory	fold_custom_width[50000]	110.7 KB	114.8 KB	-3.56%
❌	Memory	split_numeric_suffix	115.2 KB	119.3 KB	-3.43%
❌	Memory	df_deep_directory	115.4 KB	119.5 KB	-3.42%
❌	Memory	join_custom_separator	120.7 KB	124.8 KB	-3.28%
❌	Memory	cksum_multiple_files	125.9 KB	130 KB	-3.15%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing wtcpython:uucore-regex (20880e0) with main (bde7873)²}

Footnotes

1. 50 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. ↩

2. No successful run was found on main (9fa399e) during the generation of this report, so bde7873 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/cut/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/timeout/timeout-group (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tail/pid-pipe (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/tail-n0f (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/rm/many-dir-entries-vs-OOM is now passing!

[Copilot]

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