Arm backend: Add LUT-based leaky_relu lowering

[oscarandersson8218]

Add option to lower quantized leaky_relu through TOSA TABLE instead of decomposing it into clamp, mul, and add. Add an Arm pass pipeline config switch so callers can enable the table-based lowering rather than the old decomposition.

cc @digantdesai @freddan80 @per @zingo @mansnils @Sebastian-Larsson @robell @rascani

[pytorch-bot]

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✅ You can merge normally! (2 Unrelated Failures)

As of commit 6c98ce8 with merge base ec52125 ():

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

• pull / test-qnn-testsuite-linux / test-backend-linux (qnn, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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-nxp-neutron / linux-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[robell]

Arm Backend only changes. As Oscar is on PTO I'll merge these.