<!--- 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 -->

repo: https://github.com/ansible/ansible-examples.git
    dest: /src/ansible-examples
    refspec: '+refs/pull/*:refs/heads/*'
- name: Create git archive from repo
  ansible.builtin.git:
    repo: https://github.com/ansible/ansible-examples.git
    dest: /src/ansible-examples
    archive: /tmp/ansible-examples.zip
- name: Clone a repo with separate git directory
  ansible.builtin.git:
    repo: https://github.com/ansible/ansible-examples.git
    dest: /src/ansible-examples
    separate_git_dir: /src/ansible-examples.git
- name: Example clone of a single branch
  ansible.builtin.git:
    repo: https://github.com/ansible/ansible-examples.git
    dest: /src/ansible-examples
    single_branch: yes
    version: master
- name: Avoid hanging when http(s) password is missing
  ansible.builtin.git:
    repo: https://github.com/ansible/could-be-a-private-repo
    dest: /src/from-private-repo
  environment:
    GIT_TERMINAL_PROMPT: 0 # reports "terminal prompts disabled" on missing password
    # or GIT_ASKPASS: /bin/true # for git before version 2.3.0, reports "Authentication failed" on missing password
'''
RETURN = '''
after:
    description: Last commit revision of the repository retrieved during the update.