Make stream push packets to sinks

Now that decoder and recorder implement the packet sink trait, make
stream push packets to the sinks without depending on the concrete sink
types.

app/src/scrcpy.c

@@ -336,7 +336,15 @@ scrcpy(const struct scrcpy_options *options) {
 
     av_log_set_callback(av_log_callback);
 
-    stream_init(&stream, server.video_socket, dec, rec);
+    stream_init(&stream, server.video_socket);
+
+    if (dec) {
+        stream_add_sink(&stream, &dec->packet_sink);
+    }
+
+    if (rec) {
+        stream_add_sink(&stream, &rec->packet_sink);
+    }
 
     if (options->display) {
         if (options->control) {