##### 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

```

description: Image inspection results for the affected image.
    returned: success
    type: dict
    sample: {}
'''
import os
import re
import traceback
from distutils.version import LooseVersion
from ansible.module_utils.docker.common import (
    docker_version,
    AnsibleDockerClient,
    DockerBaseClass,
    is_image_name_id,
    is_valid_tag,
    RequestException,
)
from ansible.module_utils._text import to_native
if docker_version is not None:
    try:
        if LooseVersion(docker_version) >= LooseVersion('2.0.0'):
            from docker.auth import resolve_repository_name
        else:
            from docker.auth.auth import resolve_repository_name
        from docker.utils.utils import parse_repository_tag
        from docker.errors import DockerException
    except ImportError:
        
        pass
class ImageManager(DockerBaseClass):