Provide "webfiles" API to do implicit FilePath search

[roman-khimov]

Is your feature request related to a problem? Please describe.

I'm always frustrated when people have to do dances around our gateway to host some static content from it. Currently it's rewriting required to go from URL/somewhere/something.html to get_by_attribute/CID/FilePath/somewhere/something.html. Doable, sure, but something to think about for users and operators (even ourselves, it's easy to break something here).

Describe the solution you'd like

Implement new API that would basically do the same get_by_attribute trick, but internally. So that we'd get URLs like (similar to) https://http.fs.neo.org/HXSaMJXk2g8C14ht8HSi7BBaiYZ1HeWh2xnWPGQCg4H6/1388-1710261951/index.html served from the gateway directly (currently it works via rewrites).

Describe alternatives you've considered

Leaving as is with people suffering.

Additional context

Discord is a source of ideas if you're to read carefully.