[executorch][serialization] Format program.fbs with consistent whitespace

[pytorchbot]

This PR was created by the merge bot to help merge the original PR into the main branch.
ghstack PR number: #6680
^ Please use this as the source of truth for the PR details, comments, and reviews
ghstack PR base: https://github.com/pytorch/executorch/tree/gh/lucylq/17/base
ghstack PR head: https://github.com/pytorch/executorch/tree/gh/lucylq/17/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/main
Merge bot PR head: https://github.com/pytorch/executorch/tree/gh/lucylq/17/orig
@diff-train-skip-merge

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/6809

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❌ 3 New Failures

As of commit 41b196c with merge base dc41596 ():

NEW FAILURES - The following jobs have failed:

• Build documentation / build (buck2) / Build doc (gh)
  ##[error]No files were found with the provided path: /home/ec2-user/actions-runner/_work/_temp/artifacts/. No artifacts will be uploaded.
• pull / android / run-emulator (gh)
  ##[error]The process '/usr/bin/sh' failed with exit code 1
• pull / test-llama-runner-qnn-linux (fp32, qnn) / linux-job (gh)
  Invalid image name executorch-ubuntu-22.04-qnn-sdk

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