##### SUMMARY
docker_image module is missing etc_hosts parameter even if this is documented and accepted by docker.build() as  of https://docker-py.readthedocs.io/en/stable/images.html

The same argument is accepted by docker_run but the lack of support here prevents us from building images when extra_hosts is needed.

I mention that the only reason why I propose using `etc_hosts` is in order to keep it in sync with already existing implementation from `docker_container` module which accepts `etc_hosts` which is translated to `extra_hosts` on docker-python-api.

I would personally prefer to use the same names as docker-api but this would require changing docker_container too.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
docker_image

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible-devel
```

##### 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. -->


##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->


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

<!--- Paste verbatim command output between quotes -->
```paste below

```

'''
        Handles state = 'absent', which removes an image.
        :return None
        '''
        name = self.name
        if is_image_name_id(name):
            image = self.client.find_image_by_id(name)
        else:
            image = self.client.find_image(name, self.tag)
            if self.tag:
                name = "%s:%s" % (self.name, self.tag)
        if image:
            if not self.check_mode:
                try:
                    self.client.remove_image(name, force=self.force_absent)
                except Exception as exc:
                    self.fail("Error removing image %s - %s" % (name, str(exc)))
            self.results['changed'] = True
            self.results['actions'].append("Removed image %s" % (name))
            self.results['image']['state'] = 'Deleted'
    def archive_image(self, name, tag):