Enable most unittests on python3 (just some vault unittests and a logging one left) (#17240)

Make some python3 fixes to make the unittests pass:

* galaxy imports
* dictionary iteration in role requirements
* swap_stdout helper for unittests
* Normalize to text string in a facts.py function

test/units/cli/test_galaxy.py

@@ -25,7 +25,6 @@ import tarfile
 import tempfile
 
 from mock import patch
-from nose.plugins.skip import SkipTest
 
 from ansible.compat.six import PY3
 from ansible.compat.tests import unittest
@@ -34,13 +33,9 @@ from mock import patch, call
 import ansible
 from ansible.errors import AnsibleError, AnsibleOptionsError
 
-from nose.plugins.skip import SkipTest
-
-if PY3:
-    raise SkipTest('galaxy is not ported to be py3 compatible yet')
-
 from ansible.cli.galaxy import GalaxyCLI
 
+
 class TestGalaxy(unittest.TestCase):
     @classmethod
     def setUpClass(cls):