Add pre-commit hook to verify static analysis passes & format is correct (#11941)

Adds a pre-commit hook that you can install to verify that `dart analyze --fatal-infos` and the package format are correct when you make a call to `git commit`. Intended to ensure agents commit code that meets are quality standards.

Also makes the following updates the plugins tool:

- Adds `--run-on-staged-packages` flag that allows the command to only run on files with staged changes. This flag cannot be run with any other flags that filter packages where the command runs (like `--run-on-dirty-packages`)
- Adds optimization to the format tool to avoid invoking native tool chains to format when non-native files are modified

Miscellaneous notes:

- `script/githooks/bin/install_hooks.dart` is the script to install the hook that devs would need to run to use it.
- I modeled the new `githooks` directory like https://github.com/flutter/flutter/tree/master/engine/src/flutter/tools/githooks to make it easier for folks to add new hooks

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