fix(ext/node): detect non-mtime stat changes in StatWatcher (#33950)
`fs.watchFile`'s `StatWatcher` only compared `mtime` between polls, so
metadata-only changes (chmod/chown), file replacements that preserved
mtime, and changes too small for mtime resolution went undetected. The
`bigint` option was also accepted but never reached the listener. Match
libuv's `uv_fs_poll_t` field comparison and pass `bigint` through to
the stat conversion.
Fixes #23049
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Co-authored-by: fibibot <fibibot@users.noreply.github.com>