* Check and install libvirt with Homebrew
macOS does not have apt, dnf or yum. Add checking for homebrew for
installing libvirt.
* Use platform timeout for tests
* Add timeout detection to test/util.sh
* Use $timeout for shell test requiring timeout
The mgmt graph depends on state tracking to eliminate redundant pokes.
With the Watch loop now able to produce events quickly, it should no
longer play a part in determining the vertex state. This simplifies the
resource API as well!
