Adds Path to platform.File and refactors tests (#1431)

Signed-off-by: Adrian Cole <adrian@tetrate.io>
Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
Co-authored-by: Edoardo Vacchi <evacchi@users.noreply.github.com>

internal/sysfs/dirfs.go

@@ -42,7 +42,11 @@ func (d *dirFS) Open(name string) (fs.File, error) {
 
 // OpenFile implements FS.OpenFile
 func (d *dirFS) OpenFile(path string, flag int, perm fs.FileMode) (platform.File, syscall.Errno) {
-	return platform.OpenFile(d.join(path), flag, perm)
+	f, errno := platform.OpenFile(d.join(path), flag, perm)
+	if errno != 0 {
+		return nil, errno
+	}
+	return platform.NewFsFile(path, f), 0
 }
 
 // Lstat implements FS.Lstat