##### SUMMARY
add_host will return 'changed' for every invocation, it does not matter if the host already existed and no changes were actually made to inventory

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
add_host
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
2.7, 2.8, 2.9, 2.10
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
all

##### STEPS TO REPRODUCE

Simplest example, but also happens when specifying variables and/or groups

test.yml
```yaml
- hosts: localhost
  gather_facts: false
  tasks:
    - add_host: name=testhost
```
test_inv.ini
```ini
testhost
```
run:
``` ansible-playbook -i test_inv.ini test.yml```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
```
 _________________
< TASK [add_host] >
 -----------------
       \   ,__,
        \  (oo)____
           (__)    )\
              ||--|| *

OK: [localhost]
```

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below
 _________________
< TASK [add_host] >
 -----------------
       \   ,__,
        \  (oo)____
           (__)    )\
              ||--|| *

changed: [localhost]
```

for handler_name in result_item['_ansible_notify']:
                                found = False
                                
                                
                                
                                
                                target_handler = search_handler_blocks_by_name(handler_name, iterator._play.handlers)
                                if target_handler is not None:
                                    found = True
                                    if target_handler.notify_host(original_host):
                                        self._tqm.send_callback('v2_playbook_on_notify', target_handler, original_host)
                                for listening_handler_block in iterator._play.handlers:
                                    for listening_handler in listening_handler_block.block:
                                        listeners = getattr(listening_handler, 'listen', []) or []
                                        if not listeners:
                                            continue
                                        listeners = listening_handler.get_validated_value(
                                            'listen', listening_handler._valid_attrs['listen'], listeners, handler_templar
                                        )
                                        if handler_name not in listeners:
                                            continue
                                        else:
                                            found = True
                                        if listening_handler.notify_host(original_host):
                                            self._tqm.send_callback('v2_playbook_on_notify', listening_handler, original_host)