Add apt_package_security_updates fact

[jle64]

Add a apt_package_security_updates fact, similar to apt_package_updates but which only lists security updates.

[tphoney]

How is this different to lines 63-67, apologies if i am missing something obvious. No caffeine yet.

[jle64]

Lines 63-67 (fact apt_security_updates) are about the number of security updates (it returns apt_package_updates[1].length), this adds the list of security updates (same array but returns the content, not the length).

(there are already facts for number of updates, list of updates, number of security updates, this adds list of security updates)

[tphoney]

@jle64 Yup i agree, totally makes sense. 👍 Apologies for what i am about to ask

Could you please have a look at replicating the facter tests https://github.com/puppetlabs/puppetlabs-apt/blob/bd3b3fbe990bfa824ebed3504c0c82175d7c7ec9/spec/unit/facter/apt_package_updates_spec.rb for this new fact.

With this new fact, could you add a line or two to the readme explaining this cool new thing.

Shout if you need a hand with either of them.

[tphoney]

Thanks for the PR #703 is merged. I just added a test.