<!--- Verify first that your feature was not already discussed on GitHub -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
The `ssh_opts` parameter relies on setting environment variables for git, such as GIT_SSH. Git did not recognize this environment variable until version 2.3.0 (see https://git-scm.com/docs/git/2.3.0), and many contemporary OSes (RHEL 7, CentOS7) include older versions of Git (1.8.3.1).

It would be useful to provide a warning in this case, similar to the warning for the `depth` parameter. E.g. "Your git version is too old to support the ssh_opts argument."

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
git.py
source control, git module

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
It would save users time when trying to troubleshoot failed git connections via SSH.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- name: clone a git repo
  git:
    repo: git@github.com:cherdt/hello_ansible.git
    dest: /opt/hello_ansible
    version: master
    ssh_opts: "{{-o IdentityFile=github_id_rsa}}"
```

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

version_added: '2.11'
    track_submodules:
        description:
            - If C(yes), submodules will track the latest commit on their
              master branch (or other branch specified in .gitmodules).  If
              C(no), submodules will be kept at the revision specified by the
              main project. This is equivalent to specifying the --remote flag
              to git submodule update.
        type: bool
        default: 'no'
        version_added: "1.8"
    verify_commit:
        description:
            - If C(yes), when cloning or checking out a I(version) verify the
              signature of a GPG signed commit. This requires git version>=2.1.0
              to be installed. The commit MUST be signed and the public key MUST
              be present in the GPG keyring.
        type: bool
        default: 'no'
        version_added: "2.0"
    archive:
        description:
            - Specify archive file path with extension. If specified, creates an
              archive file of the specified format containing the tree structure
              for the source tree.
              Allowed archive formats ["zip", "tar.gz", "tar", "tgz"].
            - This will clone and perform git archive from local directory as not
              all git servers support git archive.
        type: path
        version_added: "2.4"