Utils: Replace FileChooser::path() by filePath().toString()

Keep the old method for now to ease downstream porting.

The change is kept mechanical, there's a lot of cleanup possible now
on the user code side.

Change-Id: I936baedd45b7ba057f1c789a1bec896886f48eff
Reviewed-by: André Hartmann <aha_1980@gmx.de>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/languageclient/languageclientsettings.cpp

@@ -890,7 +890,7 @@ StdIOSettingsWidget::StdIOSettingsWidget(const StdIOSettings *settings, QWidget
 
 QString StdIOSettingsWidget::executable() const
 {
-    return m_executable->path();
+    return m_executable->filePath().toString();
 }
 
 QString StdIOSettingsWidget::arguments() const