Clear and concise description of the problem

When using the Custom Icons feature in unplugin-icons, the custom icons cannot be previewed automatically in VS Code with the vscode-iconify extension.

Suggested solution

I noticed that vscode-iconify has added a new configuration option customCollectionJsonPaths to load custom icon collections.

It would be great if unplugin-icons could:

• Automatically generate an icons.json file in IconifyJSON format for Custom Icons,
• Or provide built-in integration so that custom icons from unplugin-icons can be recognized and previewed by iconify](https://github.com/antfu/vscode-iconify) automatically without manual configuration.

This would greatly improve the developer experience when using custom icons with unplugin-icons and vscode-iconify together.

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.