version_added for deprecated modules (#36)

* version_added for deprecated modules

Modules are deprecated by renaming so they start with "_".
This means we will not find an existing module with that
name, so look up the original name, i.e. without the leading '_'.

* Deal with aliased/symlinked modules

ansible_testing/modules.py

@@ -181,7 +181,11 @@ class ModuleValidator(Validator):
             return False
 
     def _is_new_module(self):
-        return not module_loader.has_plugin(self.name)
+        if self.name.startswith("_") and not os.path.islink(self.name):
+            # This is a deprecated module, so look up the *old* name
+            return not module_loader.has_plugin(self.name[1:])
+        else:
+            return not module_loader.has_plugin(self.name)
 
     def _check_interpreter(self, powershell=False):
         if powershell: