Support storage pool resource

[zeenix]

Openshift 4.0 Installer currently uses the default storage pool. If this pool doesn't exist, it can't do anything but error out. Since the default is not guaranteed by libvirt (it's a virt-install and virt-manager thing), it'd be useful for users like Openshift Installer to be able to be able to create the pool if it doens't exist already. I already have a WIP patch to add storage pool resource, which I'm hopefully going to finish up and submit soon in a PR.

Please note that while my use case is Openshift 4.0 Installer, this issue is not unique to that, as you can see from #446 and #75.

[MalloZup]

thx @zeenix for bringing this up. we have actually another issue regarding this. Imho we can continue the follow up here: #435

[MalloZup]

i'm closing this as duplicata. but any helps is welcome in this direction. thx! and cu on the other issue 🚀