[FEATURE] Support metadata parsing plugin

[vuhe]

LANraragi can retrieve metadata such as author, language, etc. by calling plugins through URLs in tags. A method can be used to automatically or periodically update newly added comics to obtain metadata information.

A rust interface can be developed to enable plugins to implement the interface and dynamically load it at runtime to scrape metadata.

Considering the language characteristics of Rust, dynamic loading may be a bit difficult. As an alternative approach, it is possible to pass the information to be parsed, such as file name, URL, etc., by calling shell scripts, and then modify the metadata information through parsing shell output or HTTP API calls.

There are many metadata scraping plugins in Komga's community that require changing metadata through HTTP API, which seems a bit complicated for management software because video management apps like Jellyfin can support metadata scraping through plugins.