##### 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]
```

self.add_tqm_variables(task_vars, play=iterator._play)
                templar = Templar(loader=self._loader, variables=task_vars)
                if not handler.cached_name:
                    handler.name = templar.template(handler.name)
                    handler.cached_name = True
                self._queue_task(host, handler, task_vars, play_context)
                if templar.template(handler.run_once) or bypass_host_loop:
                    break
        
        host_results = self._wait_on_handler_results(iterator, handler, notified_hosts)
        included_files = IncludedFile.process_include_results(
            host_results,
            iterator=iterator,
            loader=self._loader,
            variable_manager=self._variable_manager
        )
        result = True
        if len(included_files) > 0:
            for included_file in included_files:
                try:
                    new_blocks = self._load_included_file(included_file, iterator=iterator, is_handler=True)
                    
                    
                    for block in new_blocks:
                        iterator._play.handlers.append(block)
                        for task in block.block:
                            task_name = task.get_name()
                            display.debug("adding task '%s' included in handler '%s'" % (task_name, handler_name))
                            task.notified_hosts = included_file._hosts[:]
                            result = self._do_handler_run(