feat_wasm: add head to the WASM-compatible utilities

[sylvestre]

No description provided.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/cut/cut-huge-range is now passing!
Congrats! The gnu test tests/unexpand/bounded-memory is now passing!

[oech3]

   Compiling hashbrown v0.16.1
warning: ignoring -C extra-filename flag due to -o flag

error[E0433]: failed to resolve: could not find `unix` in `os`
   --> src/uucore/src/lib/features/fs.rs:786:18
    |
786 |     use std::os::unix::fs::MetadataExt;
    |                  ^^^^ could not find `unix` in `os`
    |
note: found an item that was configured out
   --> /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/os/mod.rs:36:9
note: the item is gated here
   --> /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/os/mod.rs:28:1
note: found an item that was configured out
   --> /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/os/mod.rs:85:9
note: the item is gated here
   --> /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/os/mod.rs:84:1

For more information about this error, try `rustc --explain E0433`.
warning: `uucore` (lib) generated 1 warning
error: could not compile `uucore` (lib) due to 1 previous error; 1 warning emitted

[sylvestre]

yeah, it is fixed by a previous PR

[codspeed-hq]

Merging this PR will degrade performance by 5.1%

⚠️ 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

❌ 1 regressed benchmark
✅ 303 untouched benchmarks
⏩ 46 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	cp_large_file[16]	263.6 µs	277.8 µs	-5.1%

---

_{Comparing sylvestre:wasm-pr4 (35afdaa) with main (1e81775)}

Footnotes

1. 46 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:

Congrats! The gnu test tests/printf/printf-surprise is now passing!