qemu_capabilities: Add QEMU_CAPS_QUERY_CURRENT_MACHINE

qemu_capabilities: Add QEMU_CAPS_QUERY_CURRENT_MACHINE

QEMU commit 46ea94ca9cf ("qmp: query-current-machine with
wakeup-suspend-support") added a new QMP command called
'query-current-machine' that retrieves guest parameters that
can vary in the same machine model (e.g. ACPI support for x86 VMs
depends on the '--no-acpi' option). Currently, this API has a single
flag, 'wakeup-suspend-support', that indicates whether the guest has
the capability of waking up from suspended state.

Introduce a libvirt capability that reflects whether qemu has the
monitor command.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>