Move dqlite in its own systemd process

[ktsakalozos]

Moving dqlite in its own separate process.

The benefits:

• improved visibility, separate logs
• improve stability, crashes in kubelite will not stop dqlite
• reduce upstream patching

This PR touches the following:

• in snapcraft.yaml
  • new k8s-dqlite daemon with k8s-dqlite and k8s-dqlite-env for configuring it
  • compile the k8s-dqlite project
• inspection script updated
• remove the k8s patches for dqlite
• adding a small patch for kubectl get clusterstatuses that is failing when etcd ep is a socket
• join.py and agent.py updated to handle the new service during cluster formation
• dbctl updated with the right socket path
• upgrade scripts updated to handle the new service when transitioning to/from a etcd/dqlite setup