Introduce QuicUtils::InvertPerspective and refactor code to use it

gfe-relnote: quic perspective refactor, no behavior change
PiperOrigin-RevId: 255318447
Change-Id: I10a7cb3478382f851d3f5a1293a248918ec95844
diff --git a/quic/core/qpack/qpack_receive_stream_test.cc b/quic/core/qpack/qpack_receive_stream_test.cc
index d324a0f..121043f 100644
--- a/quic/core/qpack/qpack_receive_stream_test.cc
+++ b/quic/core/qpack/qpack_receive_stream_test.cc
@@ -55,12 +55,11 @@
             SupportedVersions(GetParam().version))),
         session_(connection_) {
     session_.Initialize();
-    PendingStream* pending = new PendingStream(
-        QuicUtils::GetFirstUnidirectionalStreamId(
-            GetParam().version.transport_version,
-            perspective() == Perspective::IS_CLIENT ? Perspective::IS_SERVER
-                                                    : Perspective::IS_CLIENT),
-        &session_);
+    PendingStream* pending =
+        new PendingStream(QuicUtils::GetFirstUnidirectionalStreamId(
+                              GetParam().version.transport_version,
+                              QuicUtils::InvertPerspective(perspective())),
+                          &session_);
     qpack_receive_stream_ = QuicMakeUnique<QpackReceiveStream>(pending);
     delete pending;
   }