Fix issues with Meson tests

- set temporary directory for launcher
- check for finding meson tool instead of crashing
- use GUILESS_MAIN since it doesn't use gui

Change-Id: I3f8de658d9ccbec3efb260cf2d58e27720e78d47
Reviewed-by: Alexis Jeandet <alexis.jeandet@member.fsf.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/mesonprojectmanager/tests/testmesonwrapper.cpp

@@ -27,6 +27,7 @@
 
 #include <utils/launcherinterface.h>
 #include <utils/singleton.h>
+#include <utils/temporarydirectory.h>
 
 #include <QCoreApplication>
 #include <QDir>
@@ -50,6 +51,8 @@ class AMesonWrapper : public QObject
 private slots:
     void initTestCase()
     {
+        Utils::TemporaryDirectory::setMasterTemporaryDirectory(QDir::tempPath()
+                                                               + "/mesontest-XXXXXX");
         Utils::LauncherInterface::setPathToLauncher(qApp->applicationDirPath() + '/'
                                                     + QLatin1String(TEST_RELATIVE_LIBEXEC_PATH));
     }
@@ -120,5 +123,5 @@ private slots:
 private:
 };
 
-QTEST_MAIN(AMesonWrapper)
+QTEST_GUILESS_MAIN(AMesonWrapper)
 #include "testmesonwrapper.moc"