Reland "Reland "Remove our stream << overloads from non-test build targets.""

This is a reland of d7ee72041f882c023c73e27a7436c626c4e43604

Original change's description:
> Reland "Remove our stream << overloads from non-test build targets."
>
> This is a reland of c841d18d257ba8e4ed7d77d105e3c46006bb1e7e
>
> Original change's description:
> > Remove our stream << overloads from non-test build targets.
> >
> > Most are removed entirely, but RtcErrorType, RtpTransceiverDirection, IPAddress and
> > SocketAddress are kept behind gtest's #ifdef UNIT_TEST.
> >
> > Bug: webrtc:8982
> > Change-Id: I36db19891e7d25aeacb08b9a08aa2b4004765e70
> > Reviewed-on: https://webrtc-review.googlesource.com/64143
> > Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
> > Reviewed-by: Benjamin Wright <benwright@webrtc.org>
> > Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > Reviewed-by: Åsa Persson <asapersson@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#22916}
>
>
> Bug: webrtc:8982
> Change-Id: Ibe08c6270e5e693eb661a6ce9e8f074b34ef8123
> Reviewed-on: https://webrtc-review.googlesource.com/71161
> Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
> Reviewed-by: Jonas Olsson <jonasolsson@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22949}

TBR=deadbeef@webrtc.org,kwiberg@webrtc.org,asapersson@webrtc.org,jonasolsson@webrtc.org,benwright@webrtc.org

Bug: webrtc:8982
Change-Id: I29247d1c28e99af36ef228d8c75b4adecbd7b199
Reviewed-on: https://webrtc-review.googlesource.com/72681
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Jonas Olsson <jonasolsson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23092}
diff --git a/pc/rtpmediautils.h b/pc/rtpmediautils.h
index 6de6f8f..5f02d89 100644
--- a/pc/rtpmediautils.h
+++ b/pc/rtpmediautils.h
@@ -44,6 +44,14 @@
 // Returns an unspecified string representation of the given direction.
 const char* RtpTransceiverDirectionToString(RtpTransceiverDirection direction);
 
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& os,             // no-presubmit-check TODO(webrtc:8982)
+    RtpTransceiverDirection direction) {
+  return os << RtpTransceiverDirectionToString(direction);
+}
+#endif  // UNIT_TEST
+
 }  // namespace webrtc
 
 #endif  // PC_RTPMEDIAUTILS_H_