Support management of Swap unit files

[traylenator]

Pull Request (PR) description

Let .swap unit files be managed with systemd::manage_dropin and systemd::manage_unit.

For example:

systemd::manage_unit{'swapfile.swap':
  ensure        => 'present',
  active        => true,
  enable        => true,
  unit_entry    => {
    'Description' => 'Enable a swapfile at /swapfile',
  }
  swap_entry    => {
    'What' => '/swapfile',
  }
  install_entry => {
    'WantedBy' => 'multi-user.target',
  },
}

• https://www.freedesktop.org/software/systemd/man/latest/systemd.swap.html

[kenyon]

Huh, looks like this can pretty much replace our entire swap_file module. https://github.com/voxpupuli/puppet-swap_file