##### 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

```

self.fail("Error loading image %s. Specified path %s does not exist." % (self.name,
                                                                                             self.load_path))
                image_name = self.name
                if self.tag:
                    image_name = "%s:%s" % (self.name, self.tag)
                self.results['actions'].append("Loaded image %s from %s" % (image_name, self.load_path))
                self.results['changed'] = True
                if not self.check_mode:
                    self.results['image'] = self.load_image()
            elif self.source == 'pull':
                
                self.results['actions'].append('Pulled image %s:%s' % (self.name, self.tag))
                self.results['changed'] = True
                if not self.check_mode:
                    self.results['image'], dummy = self.client.pull_image(self.name, tag=self.tag)
            elif self.source == 'local':
                if image is None:
                    name = self.name
                    if self.tag:
                        name = "%s:%s" % (self.name, self.tag)
                    self.client.fail('Cannot find the image %s locally.' % name)
            if not self.check_mode and image and image['Id'] == self.results['image']['Id']:
                self.results['changed'] = False
        if self.archive_path:
            self.archive_image(self.name, self.tag)
        if self.push and not self.repository:
            self.push_image(self.name, self.tag)
        elif self.repository:
            self.tag_image(self.name, self.tag, self.repository, push=self.push)
    def absent(self):