ec2_group_facts tag list should have case preserved (ansible#24760)

Tags should retain case, and should not be snake cased.
Easiest way to do this is to snake before converting tag
list as while that affects the keys of the boto3 tag lists,
it doesn't affect the values. Need to use `tag_value_key_name`
and `tag_name_key_name` following recent change to
`boto3_tag_list_to_ansible_dict`, which used to handle both
`key`/`Key` and `value`/`Value`

lib/ansible/modules/cloud/amazon/ec2_group_facts.py

@@ -153,11 +153,13 @@ def main():
     except ClientError as e:
         module.fail_json(msg=e.message, exception=traceback.format_exc())
 
-    # Modify boto3 tags list to be ansible friendly dict and then camel_case
     snaked_security_groups = []
     for security_group in security_groups['SecurityGroups']:
-        security_group['Tags'] = boto3_tag_list_to_ansible_dict(security_group['Tags'])
-        snaked_security_groups.append(camel_dict_to_snake_dict(security_group))
+        # Modify boto3 tags list to be ansible friendly dict
+        # but don't camel case tags
+        security_group = camel_dict_to_snake_dict(security_group)
+        security_group['tags'] = boto3_tag_list_to_ansible_dict(security_group['tags'], tag_name_key_name='key', tag_value_key_name='value')
+        snaked_security_groups.append(security_group)
 
     module.exit_json(security_groups=snaked_security_groups)