dir: add "about" and "usage" instead of being "ls"

[w007878]

resolves #10361

Use the same approach for base64/base32

[sylvestre]

please add tests to make sure we don't regress in the future

[w007878]

please add tests to make sure we don't regress in the future

Thanks. On it.

[github-actions]

GNU testsuite comparison:

Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[codspeed-hq]

Merging this PR will degrade performance by 3.52%

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 280 untouched benchmarks
⏩ 38 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	du_wide_tree[(5000, 500)]	1.2 MB	1.2 MB	-3.52%
⚡	Memory	cp_large_file[16]	116.9 KB	103 KB	+13.5%

---

_{Comparing w007878:fix/dir-vdir-help (d42681a) with main (b302bbe)}

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:

GNU test failed: tests/dd/stderr. tests/dd/stderr is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/tac/tac-2-nonseekable. tests/tac/tac-2-nonseekable is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/tail/follow-stdin. tests/tail/follow-stdin is passing on 'main'. Maybe you have to rebase?

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/follow-name (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/dd/stderr is no longer failing!
Congrats! The gnu test tests/tac/tac-2-nonseekable is no longer failing!
Congrats! The gnu test tests/tail/follow-stdin 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)