##### 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

```

container_limits:
    description:
      - A dictionary of limits applied to each container created by the build process.
      - Please use I(build.container_limits) instead. This option will be removed in Ansible 2.12.
    type: dict
    suboptions:
      memory:
        description:
          - Set memory limit for build.
        type: int
      memswap:
        description:
          - Total memory (memory + swap), -1 to disable swap.
        type: int
      cpushares:
        description:
          - CPU shares (relative weight).
        type: int
      cpusetcpus:
        description:
          - CPUs in which to allow execution, e.g., "0-3", "0,1".
        type: str
    version_added: "2.1"
  use_tls:
    description:
      - "DEPRECATED. Whether to use tls to connect to the docker daemon. Set to
        C(encrypt) to use TLS. And set to C(verify) to use TLS and verify that
        the server's certificate is valid for the server."
      - "NOTE: If you specify this option, it will set the value of the I(tls) or
        I(tls_verify) parameters if not set to I(no)."