Add virsh qemu-agent-command test cases

The virsh qemu-agent-command is for send QEMU agent command directly
from virsh, which benefit debugging for devel or well knowledged user.

The qemu-* commands are not with support in RHEL products, so the testing
strategy is mainly focus on return status and libvirtd status after
command been executed.

Signed-off-by: Wayne Sun <gsun@redhat.com>
Add virsh qemu-attach test cases

The virsh qemu-attach is for attach QEMU process from virsh, the command
is requires the use of libvirt-qemu.so, and is therefore explicitly
unsupported by upstream libvirt folks. The whole idea of qemu-attach is
a development crutch and not a highly reliable mechanism.

So the testing strategy is mainly focus on libvirtd status after
command been executed.

Check more details in bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1063837
https://bugzilla.redhat.com/show_bug.cgi?id=995312
https://bugzilla.redhat.com/show_bug.cgi?id=1010617

Signed-off-by: Wayne Sun <gsun@redhat.com>