Generalize and simplify permute fusion. (#18254)

[abeakkas]

Summary:

The old algorithm can't handle the case where intermediate permutes have multiple users. Updating to a more concise and general approach.

Differential Revision: D97000790

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/18254

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❌ 1 New Failure, 3 Unrelated Failures

As of commit 855798f with merge base 94e9ca6 ():

NEW FAILURE - The following job has failed:

• pull / unittest-editable / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / test-moshi-linux / linux-job (gh) (trunk failure)
  E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/libs/libssh/libssh-gcrypt-4_0.9.6-2ubuntu0.22.04.6_amd64.deb 404 Not Found [IP: 91.189.92.23 80]
• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[meta-codesync]

@abeakkas has exported this pull request. If you are a Meta employee, you can view the originating Diff in D97000790.

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