Add skip_names and LoRALinear guard to replace_linear_with_split_linear

[lucylq]

Skip LoRALinear modules to prevent splitting lora_a/lora_b sub-layers.
Add skip_names parameter so callers can prevent splitting specific
named children (needed for POSITIONAL weight sharing with CoreML).

Authored with Claude.

[lucylq]

Stack from ghstack (oldest at bottom):

• [wip] Add CI test for CoreML LoRA multimethod export #18354
• [wip] Add --method argument to CoreML static LLM runner #18355
• Add LoRA multimethod export to CoreML static LLM export #18347
• -> Add skip_names and LoRALinear guard to replace_linear_with_split_linear #18346
• Add LoRA support to StaticAttention for split_mha=False #18345
• Refactor: extract _prepare_eager_model() from CoreML export main() #18343

[pytorch-bot]

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❌ 1 New Failure, 3 Pending, 2 Unrelated Failures

As of commit d58628d with merge base dd7464a ():

NEW FAILURE - The following job has failed:

• pull / test-voxtral-realtime-xnnpack-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 1d3d3ea9476e9c0324d41a65d1f09a1a18efa08232f964d7f21a48c7a6abd972 /exec failed with exit code 1

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / unittest-editable / windows / windows-job (gh) (matched win rule in flaky-rules.json)
  ##[error]The operation was canceled.

BROKEN TRUNK - The following job failed but was present on the merge base:

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

• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[lucylq]

in the next PR, this ends up being 'wqs', 'wks', 'wvs', 'wos'. Regular linear and LoraLinear both have to be skipped.