<!--- 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 -->

if int(dnf.__version__.split(".")[0]) >= 2:
            pkgs = list(sorted(self.base.add_remote_rpms(list(filenames)), reverse=True))
        else:
            pkgs = []
            try:
                for filename in filenames:
                    pkgs.append(self.base.add_remote_rpm(filename))
            except IOError as e:
                if to_text("Can not load RPM file") in to_text(e):
                    self.module.fail_json(
                        msg="Error occured attempting remote rpm install of package: {0}. {1}".format(filename, to_native(e)),
                        results=[],
                        rc=1,
                    )
        if self.update_only: