QSignalSpy: prepare for de-inlining

Rename qsignalspy.qdoc to .cpp, include qsignalspy.h and add the
namespace macros.

Task-number: QTBUG-123544
Change-Id: Ibd89844018afc277e6a69e7200cdbd08befd4da2
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/testlib/CMakeLists.txt

@@ -28,7 +28,7 @@ qt_internal_add_module(Test
         qplaintestlogger.cpp qplaintestlogger_p.h
         qpropertytesthelper_p.h
         qsignaldumper.cpp qsignaldumper_p.h
-        qsignalspy.h
+        qsignalspy.cpp qsignalspy.h
         qtaptestlogger.cpp qtaptestlogger_p.h
         qteamcitylogger.cpp qteamcitylogger_p.h
         qtest.h

src/testlib/qsignalspy.cpp

@@ -1,6 +1,10 @@
 // Copyright (C) 2019 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
+#include "qsignalspy.h"
+
+QT_BEGIN_NAMESPACE
+
 /*!
     \class QSignalSpy
     \inmodule QtTest
@@ -142,3 +146,5 @@
         spy.wait(2s);
     \endcode
 */
+
+QT_END_NAMESPACE