Allow extra perms on /var/lib/icinga/rw

The Icinga module rightfully sets the proper fileperms on
the /var/lib/icinga/rw directory. However, I'm running
Icinga under a different user/group (mod_ruid2 ftw), and
as such needed to set a different group on the aforementioned
directory.

Therefore, I made the file resource a virtual one, allowing
one to overwrite it:

  File <| title == '/var/lib/icinga/rw' |> {
    owner   => 'nagios',
    group   => 'icingagui',
    recurse => false,
    backup  => false,
    require => User[ 'icingagui' ],
    notify  => Service[ 'apache' ]
  }

  realize( File['/var/lib/icinga/rw'] )