Added .dc_id() method to Downloadable, so now all media downloading code uses it to avoid FILE_MIGRATE_ERROR on downloads. Falls back to the home DC if the media doesn't specify one.
Also I replaced heavy tokio::sync::Mutex with simple std::sync::atomic::AtomicI64 which is a better fit for handing out part indices.
Added `.dc_id()` method to `Downloadable`, so now all media downloading code uses it to avoid `FILE_MIGRATE_ERROR` on downloads. Falls back to the home DC if the media doesn't specify one.
Also I replaced heavy `tokio::sync::Mutex` with simple `std::sync::atomic::AtomicI64` which is a better fit for handing out part indices.