Since PySide2 5.14, 'pyside2-rcc' and 'pyside2-uic' have been renamed into plain 'rcc' and 'uic'.
This leads FindPySide2Tools.cmake to no longer find rcc/uic, as reported in bug #4229 (https://www.freecadweb.org/tracker/view.php?id=4229) and prevents compilation.
FindPySide2Tools has been updated accordingly.
Non GNU sed on macOS expects suffix after -i option (can be empty str).
However, removing the comments from the pyside generated files is not a necessary
operation (presumably done to avoid a diff when no code changed), so simply skip the operation on macOS
