(#23316) Update yum package provider support :holdable

This commit adds support for the `holdable` package feature to the yum
package provider. If the yum versionlock plugin is available packages
can specify an ensure value of 'held' and the yum provider will use the
versionlock plugin to lock the version.

This feature has the caveat that it can only be enabled at provider load
time since provider features cannot be enabled based on a code block.
Merge branch 'pull-2137'
Merge branch 'master' of https://github.com/puppetlabs/puppet