unix: support nanosecond resolution in uv__fs_to_timespec (libuv#4951)

Remove the microsecond truncation in uv__fs_to_timespec() function to enable
full nanosecond resolution support. The utimensat() system call already
supports nanosecond precision, so the artificial truncation to microseconds
is no longer necessary.

This allows file modification and access times to be set with full nanosecond
precision instead of being limited to microsecond resolution.

Fixes the TODO comment about removing the microsecond resolution limit.

Author: AyushCodes160

src/unix/fs.c

@@ -224,13 +224,6 @@ static struct timespec uv__fs_to_timespec(double time) {
   ts.tv_sec  = time;
   ts.tv_nsec = (time - ts.tv_sec) * 1e9;
 
- /* TODO(bnoordhuis) Remove this. utimesat() has nanosecond resolution but we
-  * stick to microsecond resolution for the sake of consistency with other
-  * platforms. I'm the original author of this compatibility hack but I'm
-  * less convinced it's useful nowadays.
-  */
-  ts.tv_nsec -= ts.tv_nsec % 1000;
-
   if (ts.tv_nsec < 0) {
     ts.tv_nsec += 1e9;
     ts.tv_sec -= 1;