<!--- 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 -->
Add a --cacheonly option to the ansible yum module, similar to the --downloadonly option.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
lib/ansible/modules/packaging/os/yum.py

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
We have a group of Oracle servers that have no repository management server.  They update directly from Oracle's repositories.  Our thought is to do a "yum update --downloadonly" on all dev and prod servers.  Then we can update the dev servers first using "yum update --cacheonly" to test then updated and run the same command on the prod at a later time to make them consistent with the dev.
<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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

return True
    def _sanitize_dnf_error_msg_install(self, spec, error):
        """
        For unhandled dnf.exceptions.Error scenarios, there are certain error
        messages we want to filter in an install scenario. Do that here.
        """
        if (
            to_text("no package matched") in to_text(error) or
            to_text("No match for argument:") in to_text(error)
        ):
            return "No package {0} available.".format(spec)
        return error
    def _sanitize_dnf_error_msg_remove(self, spec, error):
        """
        For unhandled dnf.exceptions.Error scenarios, there are certain error
        messages we want to ignore in a removal scenario as known benign
        failures. Do that here.
        """
        if (
            'no package matched' in to_native(error) or
            'No match for argument:' in to_native(error)
        ):
            return (False, "{0} is not installed".format(spec))
        
        
        return (True, error)
    def _package_dict(self, package):