Use long urls instead of query parameters

[TheZoq2]

Replace

mount.mount("/list", file_request_handlers::file_list_request_handler);

with

mount.mount("/list", ..)
mount.mount("/list/{id}", ..)
mount.mount("/list/{id}/file/{id}", ..)

This will make it easier to see valid parameters for requests from the code since they would be visible in the handler declaration.