Revert fstatat on *nix and test symlinks in path_filestat calls (#1725)

* Revert fstatat on *nix and test symlinks in path_filestat calls

This commit effectively reverts too eager refactoring on my part which
resulted in incorrect `path_filestat_{get, set_times}` behaviour on
*nix hosts. In the presence of symlinks, neither of the calls would
work properly.

In order to shield ourselves from similar errors in the future, I've
augmented the `path_filestat` test cases with symlink checks as well.

* Pass appropriate flags to fstatat and utimensat

* Fix formatting

* Fix Windows build

* Expand final symlinks if follow is set on Windows

* Fix formatting

* Do not follow symlinks unless specified on Windows

* Update comments and restart CI

* Skip testing volatile atim field

crates/wasi-common/src/sys/osdir.rs

@@ -69,6 +69,19 @@ impl Handle for OsDir {
     fn create_directory(&self, path: &str) -> Result<()> {
         path::create_directory(self, path)
     }
+    fn filestat_get_at(&self, path: &str, follow: bool) -> Result<types::Filestat> {
+        path::filestat_get_at(self, path, follow)
+    }
+    fn filestat_set_times_at(
+        &self,
+        path: &str,
+        atim: types::Timestamp,
+        mtim: types::Timestamp,
+        fst_flags: types::Fstflags,
+        follow: bool,
+    ) -> Result<()> {
+        path::filestat_set_times_at(self, path, atim, mtim, fst_flags, follow)
+    }
     fn openat(
         &self,
         path: &str,