test/cm_file: add readdir tests
test/cm_file: add readdir tests

The cm_file_dir_readdir tests enumerate root, account and container
children dents, and confirm the existence of a pre-created account,
container and blob.

Signed-off-by: David Disseldorp <589a549dc9f982d9f46aeeb82a09ab6d87ccf1d8@suse.de>

ddiss/elasto,ddiss/elasto