(#22128) Fixes rpm provider's nevra regex to work in yum prefetch

Work done for #19875 changed the rpm provider's regex for parsing
package information.  The yum package provider's prefetch method relied
on the earlier version of this regex and was broken by this change,
resulting in a failure to set latest_info when using yum and a series of
warning messages in the logs.

This change adjusts the rpm NEVRA_REGEX such that the added description
info is an optional capture.
(maint) Load puppetx for yaml_backend_spec

Depending on order of specs, dependencies might or might not be loaded
for Puppet::Pops::Binder::Hiera2::YamlBackend to resolve.

Ensures that YamlBackend's prerequisites are loaded in the spec.
PuppetX will only load the PuppetX::Puppet::Hiera2Backend that
YamlBackend extends if binder is true.

This is not a particularly lovely way of doing this in a spec, but the
YamlBackend implementation is intended to be lazily loaded by the
binding system.  There may be a better way of ensuring YamlBackend is
available for testing.