fix(wasi): cp attribute preservation and symlink handling

[eduardomourar]

cp treats ENOSYS like EOPNOTSUPP when skipping optional attribute preservation (WASI has no chmod/chown at all), reads timestamps via Metadata::accessed/modified instead of the filetime crate (which panics there), creates symlinks via rustix::fs::symlink, and only errors out of --reflink when explicitly requested rather than whenever it isn't Never.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/symlink (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails 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)
Note: The gnu test tests/tail/pipe-f is now being skipped but was previously passing.
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.