Support for preemptible instances within Blazar for Blazar

Preemptible instances are instances which can be terminated by the infrastructure in case of limited resource availability, to allow higher priority instances to be launched. They can increase utilization of compute resources managed by Blazar, by filling the gaps between reservations.

Implement network reservation feature for Blazar

Summary ======== Support network reservation by adding new network resource-plugins. Problem description ================ It is only "compute host" that can be reserved by Blazar for now. A variety of resources should be supported by Blazar to improve the flexibility of resource reservation. A typical one is "net...

Soft delete functionality for Blazar

Add soft-delete functionality to Blazar SQL models and tool to manage soft-deleted data.