[Feature request] Pod metrics

[NeQuissimus]

Similar to idea of the PodsHealth trait: If there was a trait PodsMetrics or similar, which requires a way to define a load factor (maybe define it to be 0.0 <= x <= 1.0) for a Pod.

trait PodsMetrics {
  def loadFactor(podAddress: PodAddress): UIO[Float]
}

By using this load factor, a pod would report how "busy" it is (it could simply report the underlying machine's CPU usage or take into account other metrics). Such a load factor could then be exposed further and, for example, be used to implement a Kubernetes HPA. This would enable pods (in both the Kubernetes and Shardcake sense) to be added and removed automatically.