### 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 val is not None and not self.unsafe and self._is_unsafe(val):
            self.unsafe = True
    def resolve(self, key):
        '''
        The intercepted resolve(), which uses the helper above to set the
        internal flag whenever an unsafe variable value is returned.
        '''
        val = super(AnsibleContext, self).resolve(key)
        self._update_unsafe(val)
        return val
    def resolve_or_missing(self, key):
        val = super(AnsibleContext, self).resolve_or_missing(key)
        self._update_unsafe(val)
        return val
    def get_all(self):