Utils: Rename FileName to FilePath

More in line with QFileInfo terminonlogy which appears to be
best-of-breed within Qt.

Change-Id: I1d051ff1c8363ebd4ee56376451df45216c4c9ab
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/projectwindow.cpp

@@ -546,7 +546,7 @@ public:
         QString importDir = QFileDialog::getExistingDirectory(ICore::mainWindow(),
                                                               ProjectWindow::tr("Import Directory"),
                                                               dir);
-        FileName path = FileName::fromString(importDir);
+        FilePath path = FilePath::fromString(importDir);
 
         Target *lastTarget = nullptr;
         BuildConfiguration *lastBc = nullptr;