Add metadata for metro package

[Manish-316]

📝 Why & how

This pull request adds metadata for the metro package, including the following:

• GitHub URL: https://github.com/facebook/metro
• npm package name: metro
• Platform support: iOS and Android
• Description: The JavaScript bundler for React Native.

✅ Checklist

• Added library to react-native-libraries.json

• Documented in this PR how to use the feature or replicate the bug.
• Documented in this PR how you fixed or created the feature.

[Simek]

Hello @Manish-316, thanks for adding Metro to the directory! 👍

Let's move the entry at the end of the file, since we use the order for "Recently Added filter, see:

• https://github.com/react-native-community/directory?tab=readme-ov-file#how-do-i-add-a-library

Additionally, let's remove the invalid description field and add a dev flag to the entry. You can find more details about available fields here:

• https://github.com/react-native-community/directory?tab=readme-ov-file#new-library-entry-template