fix(lib): advertise real slot, speed and queue figures in search replies

Every reply to a peer's search claimed a free upload slot, no speed and
an empty queue, whatever the sharer was doing, and searchers rank
sources on exactly those fields. A reply now says whether a slot is
free, the bytes per second of the last completed upload, and how many
uploads are waiting.

soulseek-rs-lib/src/client/operations.rs

@@ -593,6 +593,9 @@ impl Client {
                                 &own_username,
                                 token,
                                 &query,
+                                ctx.has_free_upload_slot(),
+                                ctx.last_upload_speed,
+                                ctx.upload_queue.len() as u32,
                             ),
                             Err(e) => {
                                 error!("[client] IncomingSearch read: {}", e);