virsh: add `console --resume` support

virsh: add `console --resume` support

This patch adds the command line flag `--resume` to the `virsh console`
command. This resumes a paused guest after connecting to the console.
This might be handy since it's a "common" pattern to start a guest
paused, connect to the console, and then resume it so as not to miss any
console messages.

Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>