fs: remove Open method from FS interface

internal/fs/fs_local.go

@@ -18,16 +18,6 @@ func (fs Local) VolumeName(path string) string {
 	return filepath.VolumeName(path)
 }
 
-// Open opens a file for reading.
-func (fs Local) Open(name string) (File, error) {
-	f, err := os.Open(fixpath(name))
-	if err != nil {
-		return nil, err
-	}
-	_ = setFlags(f)
-	return f, nil
-}
-
 // OpenFile is the generalized open call; most users will use Open
 // or Create instead.  It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,