make file metadata (exif and others) available with VFS

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### Feature description
Recent work on Nexcloud Server makes [metadata](https://github.com/nextcloud/server/issues/40676) (such as exif information and other details) available via an API for apps and clients.
Nextcloud Server starting from release 28 exposes [Files Metadata](https://docs.nextcloud.com/server/latest/developer_manual/digging_deeper/files-metadata.html#files-metadata) API integrated with WebDAV.

This metadata should be available in VFS for virtual files. This way, this metadata can be used to sort and filter files in Windows Explorer and other Windows applications can also use this metadata.

There is also a separate enhancement request https://github.com/nextcloud/desktop/issues/6052 regarding the availability of the date taken information, which is important for sorting images chronologically.

file without metadata:
/
file with metadata: