### Summary

`ansible.template.is_template` tries to loop until it determines if the value is indeed a template.  Which means we could loop extremely large strings, that don't even remotely look like templates, before we bail.

However, we could benefit from moving `Templar.is_possibly_template` to the global scope, and testing whether the value after `jinja_env.preprocess` is even possibly a template, before doing more computationally complex validation.

### Issue Type

Feature Idea

### Component Name

lib/ansible/template/__init__.py

### Additional Information

<!--- Paste example playbooks or commands between quotes below -->
```yaml (paste below)

```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
if fullpath is None:
        b_path = to_bytes(path)
    else:
        b_path = to_bytes(fullpath)
    try:
        template_uid = pwd.getpwuid(os.stat(b_path).st_uid).pw_name
    except (KeyError, TypeError):
        template_uid = os.stat(b_path).st_uid
    temp_vars = {
        'template_host': to_text(os.uname()[1]),
        'template_path': path,
        'template_mtime': datetime.datetime.fromtimestamp(os.path.getmtime(b_path)),
        'template_uid': to_text(template_uid),
        'template_run_date': datetime.datetime.now(),
        'template_destpath': to_native(dest_path) if dest_path else None,
    }
    if fullpath is None:
        temp_vars['template_fullpath'] = os.path.abspath(path)
    else:
        temp_vars['template_fullpath'] = fullpath
    managed_default = C.DEFAULT_MANAGED_STR
    managed_str = managed_default.format(
        host=temp_vars['template_host'],
        uid=temp_vars['template_uid'],
        file=temp_vars['template_path'],
    )
    temp_vars['ansible_managed'] = to_text(time.strftime(to_native(managed_str), time.localtime(os.path.getmtime(b_path))))
    return temp_vars
def _escape_backslashes(data, jinja_env):