feat(rspack_plugin_copy): Set source_filename and copied flag when copying an asset

[ramon-villain]

Summary

This PR adds a new copied flag to the AssetInfo structure in Rspack and sets the source_filename attr when copying a file.

Key changes include:

1. Added copied field to JsAssetInfo, AssetInfo, and StatsAssetInfo structures.
2. Updated the CopyPlugin to set the copied flag and sourceFilename when copying assets.
3. Modified the stats printer to display the "copied" flag in asset information.
4. Updated TypeScript definitions and API documentation to reflect these changes.

This aligns Rspack more closely with webpack's behavior regarding copied assets.

Checklist

• Tests updated (or not required).
  • Updated CopyPlugin.test.js to include assertions for the new copied flag.
• Documentation updated (or not required).
  • Updated api.md to include the new copied field in KnownAssetInfo.

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[LingyuCoder]

LGTM, thanks