[Feature Request] Native WebDAV support

[capelo0]

Is your feature request related to a problem? Please describe.
Yes, my entire eBook library is stored in Nextcloud, and currently, there is no way to visualize or manage these eBooks through Calibre-Web without complex and unreliable workarounds.

Describe the solution you'd like
I would like Calibre-Web to support native WebDAV access, allowing users to connect their WebDAV-enabled storage solutions directly to the application.

Describe alternatives you've considered
I have tried using rclone to mount the WebDAV storage and then pass the contents to the Docker container running Calibre-Web. However, this approach does not work as the solution is cumbersome and the Library content is not passing to the Docker environments.

Additional context
Adding native WebDAV support would significantly enhance the usability of Calibre-Web for users who store their eBook libraries in cloud storage solutions like Nextcloud. This feature would eliminate the need for intermediate tools and simplify the setup process.