Fixes #49362 module dnf: install python3-dnf preferably over python2-dnf. (#49402)

* Create python3and2

Adding tests to see if dnf still works when python-2 and python-3 are installed.

* Update main.yml

Include the tests that run on python 2 and python 3, based on the package manager.

* Update dnf.py

Use python3-dnf by default, otherwise python2-dnf.

* Rename python3and2 to python3and2.yml

Rename.

lib/ansible/modules/packaging/os/dnf.py

@@ -464,10 +464,10 @@ class DnfModule(YumDnf):
 
     def _ensure_dnf(self):
         if not HAS_DNF:
-            if PY2:
-                package = 'python2-dnf'
-            else:
+            if not PY2:
                 package = 'python3-dnf'
+            else:
+                package = 'python2-dnf'
 
             if self.module.check_mode:
                 self.module.fail_json(