Create local talos machines connected to Omni via cluster create

[rothgar]

Feature Request

talosctl cluster create --omni myomni.siderolabs.com

Description

I'd like to be able to create Omni nodes for testing in a similar way to local talos clusters. We can currently do this by using images from the factory with my omni join configuration, but we can make that easier and automated for people to try it.

This could theoretically work with docker nodes, but it probably works better with qemu and maybe we should default to using the qemu provisioner when --omni is used.

I'm not sure if this should automatically create a cluster with the machines that are created or if we should just create VMs. Maybe by default we deploy a cluster template with the machines and we add a flag similar to --skip-injecting-config to allow VMs to be created and connected without adding them to a cluster.