fix(mktemp): add wasi platform support for temporary directory handling

[eduardomourar]

• Add conditional compilation for WASI target to avoid panics from std::env::temp_dir()
• Implement fallback logic in Options to read TMPDIR environment variable directly on WASI
• Update get_tmpdir_env_or_default() with WASI-specific handling for temp directory resolution
• Add #[cfg_attr] annotations to skip host path-dependent tests on WASI sandbox environment
• Ignore 14 tests that require host filesystem access when running under wasi_runner
• Ignore directory permission test on WASI due to lack of chmod support and mode parameter limitations

[codspeed-hq]

Merging this PR will not alter performance

✅ 347 untouched benchmarks
⏩ 46 skipped benchmarks¹

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_{Comparing eduardomourar:fix/mktemp-wasi (e46cdbb) with main (33df181)}

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:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/cat/splice is no longer failing!
Congrats! The gnu test tests/cut/mb-non-utf8 is no longer failing!
Congrats! The gnu test tests/mv/dir2dir is no longer failing!
Congrats! The gnu test tests/mv/mv-exchange is no longer failing!
Congrats! The gnu test tests/nl/multibyte is no longer failing!
Congrats! The gnu test tests/od/od-j is no longer failing!
Note: The gnu test tests/cp/link-heap is now being skipped but was previously passing.
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.
Congrats! The gnu test tests/dd/no-allocate is now passing!
Note: The gnu test tests/misc/write-errors was skipped on 'main' but is now failing.

[github-actions]

Binary size comparison:

Individual binary size comparison VS main (threshold: >=5% AND >=4 KB).

Total size of compared binaries: 148.93 MB (+320 KB, +0.21%)

Significant per-binary changes:
  install     1.24 MB ->    1.32 MB  (+80 KB, +6.29%)
  mkdir       1.09 MB ->    1.17 MB  (+80 KB, +7.14%)
  mkfifo      1.09 MB ->    1.16 MB  (+76 KB, +6.83%)
  mknod       1.09 MB ->    1.17 MB  (+76 KB, +6.79%)