Issue #23193: Skip numeric_owner tests on platforms where they don't make sense

In particular, the tests bomb out on Windows.  The feature is a no-op on platforms
without the pwd module or os.geteuid anyway.

Lib/test/test_tarfile.py

@@ -2279,6 +2279,8 @@ def root_is_uid_gid_0():
     return True
 
 
+@unittest.skipUnless(hasattr(os, 'chown'), "missing os.chown")
+@unittest.skipUnless(hasattr(os, 'geteuid'), "missing os.geteuid")
 class NumericOwnerTest(unittest.TestCase):
     # mock the following:
     #  os.chown: so we can test what's being called