Fix IndexError in RemovePermutesAroundElementwiseOps for rank-mismatched views (#19713)

[mcremon-meta]

Summary:

Fix an IndexError crash in the RemovePermutesAroundElementwiseOps
compiler pass that occurs when a squeeze/unsqueeze view_copy node is
included in a subgraph via upstream traversal with a permutation whose
rank does not match the view input tensor rank.

The bug manifests as IndexError: tuple index out of range in
update_view_copy at the line:

unpermuted_in = [in_shape[inverse_permute[i]] for i in range(len(in_shape))]

because inverse_permute contains indices from a rank-N permutation
but in_shape has fewer than N dimensions.

The fix adds a validation guard at the top of permute_subgraph() that
checks all view_copy nodes for rank consistency between their
node_start_permute and their input tensor shape. If a mismatch is
found, the entire subgraph optimisation is skipped, preserving graph
correctness. The return type of permute_subgraph is changed from
None to bool so the caller only marks the graph as modified when the
subgraph was actually transformed.

Also adds a regression test that constructs the exact graph pattern
(upstream unsqueeze view_copy with a 2D constant feeding into a 3D
permuted add) that triggered the crash.

Reviewed By: ethansfng

Differential Revision: D105787161

[pytorch-bot]

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❌ You can merge normally! (2 Unrelated Failures), 1 Unclassified Failure

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