Add apt_unattended_upgrades resource

[tas50]

Core Chef Resource Checklist

Before suggesting a resource for inclusion please make sure your suggestion meets these criteria for resources built into Chef:

• Automates an operating system component that ships by default on systems such as authentication, raid, disk partitions, firewalls, containers, or virtualization systems.
• Does not attempt automate 3rd party applications such as database, web, or application servers, which are best suited for cookbooks due to their fast moving nature.

Describe the resource:

This would control the apt unattended upgrades functionality.

Why should this be included out of the box?:

This is one of the last reasons to use the apt cookbook. I'd love to deprecate that cookbook

What operating systems would it run on?

Debian

Current cookbook implementation:

apt