Fix jagged test oracles

[voltjia]

Summary

• replace jagged test expectations with explicit padded and values oracles
• probe jagged_dim=1 and jagged_dim=2 independently before collecting GPU cases
• skip only layouts the installed PyTorch runtime cannot construct

Functional implementation validation before restoring the original assertion API:

pytest output:

NVIDIA: 21 passed in 34.05s
Hygon: 21 passed in 64.76s
Iluvatar: 13 passed, 8 skipped in 12.74s

Latest head b6aced9a validation after restoring the two pre-existing torch.allclose assertions:

NVIDIA: 21 passed in 25.24s
Iluvatar: 13 passed, 8 skipped in 12.07s
Hygon: not rerun because the host was temporarily unreachable via SSH

The Iluvatar skips are limited to jagged_dim=2, which its PyTorch runtime reports cannot be represented with the jagged layout.