open_by_handle: add a test for connectable file handles

open_by_handle: add a test for connectable file handles

This is a variant of generic/477 with connectable file handles.
This test uses load and store of file handles from a temp file to test
decoding connectable file handles after cycle mount and after renames.

Decoding connectable file handles after being moved to a new parent
is expected to fail on some filesystems, but not on filesystems that
do not really get unmounted in mount cycle like tmpfs, so skip this test.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>