<!--- 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 -->

state: present
- name: Autoremove unneeded packages installed as dependencies
  dnf:
    autoremove: yes
- name: Uninstall httpd but keep its dependencies
  dnf:
    name: httpd
    state: absent
    autoremove: no
- name: Install a modularity appstream with defined stream and profile
  dnf:
    name: '@postgresql:9.6/client'
    state: present
- name: Install a modularity appstream with defined stream
  dnf:
    name: '@postgresql:9.6'
    state: present
- name: Install a modularity appstream with defined profile
  dnf:
    name: '@postgresql/client'
    state: present
'''
import os
import re
import sys
from ansible.module_utils._text import to_native, to_text
from ansible.module_utils.urls import fetch_file
from ansible.module_utils.six import PY2, text_type
from distutils.version import LooseVersion
from ansible.module_utils.basic import AnsibleModule