add module level benchmark for gemma3 model

[Gasoonjia]

Stack from ghstack (oldest at bottom):

• adding cuda memory estimation support #15294
• -> add module level benchmark for gemma3 model #15241
• make aoti_torch_empty_strided support creating incontiguous tensor #15228

This diff adds a module-level benchmark for the GEMMA3 model.
Also introduce mutlmodal_benchmark.cpp to replace original voxtral_runner.cpp for benchmarking both gemma3 and voxtral model in module level.

Differential Revision: D84958564

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15241

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❌ 2 New Failures, 3 Unrelated Failures

As of commit 303dbb8 with merge base 9b744b4 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest-arm-backend-with-no-fvp (test_pytest_models) / linux-job (gh)
  RuntimeError: Command docker exec -t 26fd33401c3299b0f4b9bced9568e207e90a8ad520c3405fce0d81c5818e6e20 /exec failed with exit code 1
• pull / unittest-nxp-neutron / linux-job (gh)
  RuntimeError: Command docker exec -t 7ad6c39a9f1723e57c0f0caef0574264c38084f7ba726cc4d19ad1e3ecdf67a6 /exec failed with exit code 1

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

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

• pull / android / run-emulator (gh) (trunk failure)
  The process '/usr/bin/sh' failed with exit code 255
• pull / unittest / linux / linux-job (gh) (trunk failure)
• pull / unittest-editable / linux / linux-job (gh) (trunk failure)

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