Fix missing methods in LocalTest for Linux

Some methods are redefined in the WindowsLocalClient and the MacLocalClient, but not in the LocalTest class. This makes some tests fail on Linux because they do not cast the str from the tests into Path, most of them in test_local_move_and_rename.py with errors such as:

TypeError: unsupported operand type(s) for /: 'str' and 'str'

AttributeError: 'str' object has no attribute 'name'