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/qmljstools/qmljsmodelmanager.cpp

@@ -94,7 +94,7 @@ ModelManagerInterface::ProjectInfo ModelManager::defaultProjectInfoForProject(
             return fn && fn->fileType() == FileType::QML
                     && qmlTypeNames.contains(Utils::mimeTypeForFile(fn->filePath().toString(),
                                                                     MimeMatchMode::MatchExtension).name());
-        }), &FileName::toString);
+        }), &FilePath::toString);
         activeTarget = project->activeTarget();
     }
     Kit *activeKit = activeTarget ? activeTarget->kit() : KitManager::defaultKit();