kvm tools: Split 'kvm pause' and add 'kvm resume'

This patch seperates 'kvm pause' into 'kvm pause' and 'kvm resume',
'kvm pause' no longer acts as a switch between running and paused state but
instead just switches the instance into paused and reume is handled by
the new 'kvm resume'.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>