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##### 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
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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.
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```yaml

```

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required: false
    version_added: "1.5"
    default: "yes"
    type: bool
notes:
  - When used with a `loop:` each package will be processed individually,
    it is much more efficient to pass the list directly to the `name` option.
  - In versions prior to 1.9.2 this module installed and removed each package
    given to the yum module separately. This caused problems when packages
    specified by filename or url had to be installed or removed together. In
    1.9.2 this was fixed so that packages are installed in one yum
    transaction. However, if one of the packages adds a new yum repository
    that the other packages come from (such as epel-release) then that package
    needs to be installed in a separate task. This mimics yum's command line
    behaviour.
  - 'Yum itself has two types of groups.  "Package groups" are specified in the
    rpm itself while "environment groups" are specified in a separate file
    (usually by the distribution).  Unfortunately, this division becomes
    apparent to ansible users because ansible needs to operate on the group
    of packages in a single transaction and yum requires groups to be specified
    in different ways when used in that way.  Package groups are specified as
    "@development-tools" and environment groups are "@^gnome-desktop-environment".
    Use the "yum group list hidden ids" command to see which category of group the group
    you want to install falls into.'
  - 'The yum module does not support clearing yum cache in an idempotent way, so it
    was decided not to implement it, the only method is to use command and call the yum
    command directly, namely "command: yum clean all"
    https://github.com/ansible/ansible/pull/31450#issuecomment-352889579'
# informational: requirements for nodes
requirements: