[wip] Sync scalar types with symlink

[lucylq]

Summary

Use symlinks to sync the scalar_type.fbs files

Test plan

CI, see if there are regressions (maybe windows doesn't work well?)

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/16918

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❌ 2 New Failures, 1 Unrelated Failure

As of commit 6252f45 with merge base 914d5ff ():

NEW FAILURES - The following jobs have failed:

• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t 46c384776bb12e8bec5b41f457236f0f7d6003d3d9acc30633cbdb51937cf7bd /exec failed with exit code 1
• Test Metal Backend / test-model-metal-e2e (openai, whisper-small, non-quantized) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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

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

• Test Metal Backend / test-model-metal-e2e (openai, whisper-large-v3-turbo, non-quantized) / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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