internal: add --all option to clang-format-hook.js

[Pospelove]

[!IMPORTANT] Add --all option to clang-format-hook.js to format all files in the repository.

• Feature Addition:
  • Add --all option to clang-format-hook.js to format all files in the repository.
  • Introduce findFiles function to recursively find all files in the current directory.
• Behavior:
  • If --all is specified, formats all files with specified extensions.
  • If --all is not specified, formats only staged files as before.
• Misc:
  • Minor refactoring to separate file finding and formatting logic.

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