fix: external amd array case

[IWANABETHATGUY]

Related issue (if exists)

Summary

🤖 Generated by Copilot at 6afed73

This pull request adds a new example project to the examples/amd folder, which demonstrates how to use rspack with AMD modules and externals. It also fixes a bug in the utils.rs file of the rspack_plugin_library crate, which affected the JSON serialization of module requests.

Walkthrough

🤖 Generated by Copilot at 6afed73

• Fix a bug in JSON serialization of module requests (link)
• Add an example project that uses AMD modules and externals (link, link, link, link)
  • Create a basic HTML template for the html builtin plugin (link)
  • Define the dependencies, scripts, and side effects for the project in package.json (link)
  • Configure the rspack CLI options for AMD output and externals in rspack.config.js (link)
  • Export a default function component named App that renders a div element in src/index.jsx (link)
• Update the pnpm-lock.yaml file to include the new example project and its dependencies (link)