Add test for order=dfs with sharding (HAMT dir and multiblock file)

[lidel]

TestTrustlessCarOrderAndDuplicates introduced in #87 uses basic fixture where dir is not sharded, and every file fits in a single block.

We should add a test of order=dfs based on HAMT fixture such as already existing bafybeidbclfqleg2uojchspzd4bob56dqetqjsj27gy2cq3klkkgxtpn4i (CAR), to ensure ordering is respected when sharding of dirs and files is involved.