Allow passing arbitrary props to NextTopLoader component

[ProchaLu]

First of all, thank you for your amazing work on this library.

I have a suggestion that I believe would enhance the functionality of the NextTopLoader component. Currently, it provides several props for customization, which is great. However, I would like to propose adding a new feature that allows users to pass arbitrary props to the NextTopLoader component.

The inspiration for this feature comes from the template option in the nprogress package. With the ability to pass custom props, users like myself, for example, could add attributes such as data-test-id, which can significantly help in testing scenarios. Having the ability to set a data-test-id would allow us to easily check if the component has completed its loading process during testing.

• Loading UI Interferes with Puppeteer navigation vercel/next.js#52265

I believe this addition would make the NextTopLoader even more versatile and further improve its usability. I hope this suggestion resonates with you.

Thank you once again for your hard work and consideration of this proposal.