Refactor code for VirtualFacts (#18122)

The populate method is cut and paste on every subclass,
so we should push it up, and add a default method that is overloaded

lib/ansible/module_utils/facts.py

@@ -3080,8 +3080,13 @@ class Virtual(Facts):
             return super(cls, subclass).__new__(subclass, *arguments, **keyword)
 
     def populate(self):
+        self.get_virtual_facts()
         return self.facts
 
+    def get_virtual_facts(self):
+        self.facts['virtualization_type'] = ''
+        self.facts['virtualization_role'] = ''
+
 class LinuxVirtual(Virtual):
     """
     This is a Linux-specific subclass of Virtual.  It defines
@@ -3090,10 +3095,6 @@ class LinuxVirtual(Virtual):
     """
     platform = 'Linux'
 
-    def populate(self):
-        self.get_virtual_facts()
-        return self.facts
-
     # For more information, check: http://people.redhat.com/~rjones/virt-what/
     def get_virtual_facts(self):
         # lxc/docker
@@ -3265,14 +3266,6 @@ class FreeBSDVirtual(Virtual):
     """
     platform = 'FreeBSD'
 
-    def populate(self):
-        self.get_virtual_facts()
-        return self.facts
-
-    def get_virtual_facts(self):
-        self.facts['virtualization_type'] = ''
-        self.facts['virtualization_role'] = ''
-
 class DragonFlyVirtual(FreeBSDVirtual):
     platform = 'DragonFly'
 
@@ -3284,10 +3277,6 @@ class OpenBSDVirtual(Virtual):
     """
     platform = 'OpenBSD'
 
-    def populate(self):
-        self.get_virtual_facts()
-        return self.facts
-
     def get_virtual_facts(self):
         sysctl_path = self.module.get_bin_path('sysctl')
 
@@ -3332,10 +3321,6 @@ class HPUXVirtual(Virtual):
     """
     platform = 'HP-UX'
 
-    def populate(self):
-        self.get_virtual_facts()
-        return self.facts
-
     def get_virtual_facts(self):
         if os.path.exists('/usr/sbin/vecheck'):
             rc, out, err = self.module.run_command("/usr/sbin/vecheck")
@@ -3369,10 +3354,6 @@ class SunOSVirtual(Virtual):
     """
     platform = 'SunOS'
 
-    def populate(self):
-        self.get_virtual_facts()
-        return self.facts
-
     def get_virtual_facts(self):
 
         # Check if it's a zone