Change visiblity of rtc::ReceivedPacket to be visible

Since sockets are visible and now require the use of rtc::ReceivedPacket, it make sense
if the target is also visible.

Change-Id: I32c522b558d8058e29a5335f49e40a6122916102
Bug: webrtc:11943
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/331600
Auto-Submit: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41392}

rtc_base/network/BUILD.gn

@@ -18,6 +18,7 @@ rtc_library("sent_packet") {
 }
 
 rtc_library("received_packet") {
+  visibility = [ "*" ]
   sources = [
     "received_packet.cc",
     "received_packet.h",