Manual classification of content - Enhanced Metadata

I suggest an optional environment variable called something like CUSTOM_TAGS (or something better) with a twin feature allowing us to tag files directly on the dashboard

This would both allow users to have their files in /movies, /series, /anime or /sports folders without relying on an automated scanner && avoid getting rate limited by bypassing the torbox seach API.

We could start with the basics and then, maybe, allow users to set custom tags to have custom folders propagated through TMC.

Linked Github Issue: https://github.com/TorBox-App/torbox-media-center/issues/37