Utils: Rename PathChooser::{f,setF}ileName() to {f,setF}ilePath()

It's returning a FilePath, so it's a better fit.

Keep the old versions as inline function now to ease downstream migration.

Change-Id: I535887928018f42b92895c8b0c82527f0d55e5ca
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: André Hartmann <aha_1980@gmx.de>

src/plugins/qmakeprojectmanager/addlibrarywizard.cpp

@@ -195,7 +195,7 @@ DetailsPage::DetailsPage(AddLibraryWizard *parent)
 
     const auto pathValidator = [libPathChooser](Utils::FancyLineEdit *edit, QString *errorMessage) {
         return libPathChooser->defaultValidationFunction()(edit, errorMessage)
-                && validateLibraryPath(libPathChooser->fileName(),
+                && validateLibraryPath(libPathChooser->filePath(),
                                        libPathChooser, errorMessage);
     };
     libPathChooser->setValidationFunction(pathValidator);